So within my world there exists a faction of monks on a secluded mountain whose scientific and philosophical knowledge outstrips the outside medieval world. And with these monks being famous more for their mastery of martial arts in all their forms than any other of their achievements, it follows that they are most famous for what outsiders call the "Steel Eating Sword". So how would a mostly non-modern society go about crafting a sword that can cut through normal steel armor and weapons?

So the characteristics of this sword are as follows:

  • Able to cut through steel, e.g. through a sword raised in defense or plate armor.
  • Made like some kind of saber for cutting (based off of the nodachi, zanbato, or dandao) .
  • Made with "mysterious" materials and craftsmanship that confuse all smiths
  • Rarely needs to be sharpened.
  • Isn't affected by water or air exposure.
  • Hard to break, snaps back into shape.

As for the skill base of these monks:

  • Turn of the century level of technological knowledge (with some exceptions of more or less advanced)
  • Capable of electrolysis
  • Unified society (ample hands for labor and minds for thinking)
  • Logically based society with no constrictions based on culture or taboo.

I'm thinking iridium, tungsten, titanium, diamond integrated metals, etc.

So since my world isn't far enough into development for rules to be hard-set I do have a lot of wiggle room.

TL;DR: how to make a sword that can cut through steel armor?

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    $\begingroup$ Just use Adamantium. Its the same thing wolverines claws are made of and contains the properties you want. $\endgroup$
    – Shadowzee
    Commented May 23, 2019 at 6:27
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    $\begingroup$ What do you mean by "Turn of the century level of technological knowledge..."? There have been quite a few centuries, and it's hard to see how a faction of monks on a secluded mountain could have reached year 2000-ish tech in isolation. $\endgroup$ Commented May 23, 2019 at 6:59
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    $\begingroup$ @KerrAvon2055 Technological knowledge in any given era varies from location to location. The only monks I'm aware of who possessed swords that could cut through steel existed quite a long time ago, albeit in a galaxy far, far away. $\endgroup$
    – Ray
    Commented May 23, 2019 at 7:42
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    $\begingroup$ Surely you want a steel-cutting sword, not a steel cutting sword? $\endgroup$
    – Aaron F
    Commented May 23, 2019 at 15:25
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    $\begingroup$ @AaronF Or perhaps a steel steel-cutting cutting sword? Or even a steel-cutting steel cutting sword. $\endgroup$ Commented May 23, 2019 at 21:22

16 Answers 16


Frame challenge:

You can’t, at least with the limitations imposed

You are asking for too much, some of your points contradict each other or ask for something that's far beyond what a sword could do:

Able to cut through steel, i.e. through a sword raised in defense or plate armour.

Firstly, asking to cut through a steel sword with another sword is hard enough. The problem is if you raised your sword and I struck it with my own, your sword is going to flex and move away. Your arms may also move to absorb the blow, further reducing the force on the sword.

Second, that's not how you fight with swords anyway. It's not as simple as “swing the blade as hard as you can and cut the person”, it has more finesse than that. I won’t bore you with all the fine details about sword fighting, but I will give you the basic concept of “overly strong strikes”. Basically, if your opponent is swinging with a lot of power (as they would be if they were trying to cut through your sword), it is futile to try and match their strength with your block, if they hit the tip-end of your sword, it will move out the way anyway and you’ll be cut. If however you instead let them knock your blade aside and you step out the way, you can redirect your sword with the momentum they gave you and strike them instead, using their strength against them.

Made like some kind of saber for cutting (based of off the nodachi, zanbato, or dandao)

None of those swords you listed are ideal for a duel between sword fighters, as they don’t have large enough guards. A strike is more likely to hit you as you have very little protection, crossguards, when used correctly, protect your entire body, not just your hands. I would recommend something like the Kriegsmesser, since the blade has similarities to those swords you mentioned but the crossguard is far larger and there is a “nail” that sticks of to one side, offering even more protection.

Rarely needs to be sharpened

It will need to be sharpened often, there are no two ways about it. You are striking a fine edge against solid steel, you will need to sharpen it if nothing else but to remove the damage to the edge of the blade. Also, even the air causes steel swords to dull and require sharpening. In short, your swords will need to be sharpened fairly regularly.

isn't affected by water or air exposure Hard to break, snaps back into shape

No idea what “snaps back into shape means”, if you’re referring to the damage of a sword being repaired easily, I would just like to point out that it will always be weaker than before it was damaged.

However, steel swords could cut through iron or bronze swords

All this being said, it is still possible to achieve something similar to what you want, though not against steel. Both iron and bronze swords can be cut through with a steel one, there are a number of accounts of this.

If you were to change what swords everyone else was wielding, your answer becomes “the monks use steel swords”. Steel smithing was a “mysterious” process during the Bronze Age, it could cut through iron or bronze swords, could easily be made into any sword design you wanted, wouldn’t need sharpening as much as iron or bronze and the process of making steel stainless makes it resistant to water and air corrosion (though, to clarify, you’d want stainless spring steel or stainless tool steel, not the stainless steel cutlery, cheap pocket knives or training swords are made out of).

Here are some videos which talk about steel swords and why steel was used for swords historically:

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – L.Dutch
    Commented May 24, 2019 at 18:15
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    $\begingroup$ You could also just have the monks with superior steel, and everyone else with lower quality steel which is considerably more brittle – eg. they might lack knowledge of annealing, or their source of steel has too much carbon. $\endgroup$
    – Dan W
    Commented May 25, 2019 at 16:57

You won't be able to cut a sword as if it were paper, cloth or a bamboo, not with your constraints. Mainly because metal blades are not made of fiber, so even for a medieval sword you would need a laser for a proper cut.

What you can do is make the enemy's blade snap. Blades will snap if you bang them hard enough against hard objects. To that end, ancient chinese developed the bagua zhang dao:

A.K.A. Big Bagua Saber

That thing does not have a sharp edge, and that is by design.

Modern ones for martial arts training weight up to 2kg (~4lb), but my fencing instructors told me ancient ones could weight up to 10x 4x that. You wouldn't swing those blades like a regular one; you'd have to keep it in constant motion, switching arms and using your torso as a counterweight. The point of using that weapon in battle was that if your opponent wielded a regular 0.7 to 1.5 kg sword, blocking your blade with their own would mean their weapon would break.

And if they were using armor, taking a blow from a 4-8 kg piece of metal with a very thin profile may be lethal. The armor will bend and press your body into an unnatural shape, breaking bone and tearing ligaments. If the armor is brittle, it may not stand the reshaping and tear open.

Edit: After talking to one of my instructors, he said 10x was a gross exaggeration. Most bagua sabers wouldn't be more than 3 or 4 kg heavy, and only some (maybe ceremonial) ones would reach 8kg. Still, we broke a lot of swords when we sparred with smaller, lighter blades; it just happens that in ancient times, a blade would hardly last more than one or two battles, depending on the kind of blade. I know for sure that a 1kg sharp one parrying a 4kg blunt one will probably be damaged beyond usefulness after not too many direct hits.

Another edit: I learned some moves that I used to practice with a wooden one (which was on the light end of the spectrum, probably 1.5 to 2kg). They look like this, but are not exactly the same. The most similar part is the vertical swing followed by a low swing at 0:20.

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    $\begingroup$ The ones in the video are Wu vs. the moves you are describing are...lets just go with older. I will add a confirmation on the 9lbs (about 4kg) being a common weight for those which saw usage on the battle field based on my research and the fact that this weapon was not known for it inheritance (as apposed to other blades of the time) though I would say one or two battles is a low estimation - based on my own knowledge, research, and consultation with a T'ai chi ch'uan sifu. $\endgroup$ Commented May 25, 2019 at 4:37
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    $\begingroup$ Slight technical correction, at least according to the semantics we use in our school: If your enemy blocks a dao, their sword may break. If they correctly parry, their sword will take very little force, and almost certainly won't break. Though it'll probably still mess up that bit of the cutting edge. $\endgroup$
    – Dan W
    Commented May 25, 2019 at 16:54
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    $\begingroup$ @DanW thanks :) I have edited my answer. $\endgroup$ Commented May 25, 2019 at 17:26

Ceramic swords

We have ceramic knives today, much harder than steel (8.5 on the Mohs scale of mineral hardness, compared to 4.5 for normal steel and 7.5 to 8 for hardened steel). They keep their edges far longer than steel blades and never rust or degrade, even in very harsh conditions. They are also resistant to acid.

Ceramic blades are, however, more brittle than steel, so real-life ceramic swords will not live up to your last requirement. Your monks may have solved that problem through a secret process. In Miyazaki's Nausicaä manga (picture) and anime, the heroine wields a ceramic sword that slices through steel blades, so there is a fictional precedence.

enter image description here

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    $\begingroup$ Maybe a composite? Ceramic blade edge with a steel inner structure. Combine the properties of both materials. $\endgroup$ Commented May 23, 2019 at 10:32
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    $\begingroup$ Would probably still chip easily. Happened to my ceramic knife. But I suppose we can imagine adding fine silk threads to the ceramic mixture for greater resilience. $\endgroup$ Commented May 23, 2019 at 11:02
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    $\begingroup$ +1 for nausicaa just had the pleasure of seeing it in theaters. I've always wondered if you could find a special "mixture"for your ceramics to be less brittle $\endgroup$ Commented May 23, 2019 at 14:09
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    $\begingroup$ "May your blade chip and shatter." $\endgroup$
    – Mark
    Commented May 23, 2019 at 23:08
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    $\begingroup$ @Luaan: Exactly, Flint knives and axes were much sharper than their bronze counterparts, but a lot more brittle. There are even examples of flint swords, but they are thought to be mainly for show., as they would shatter in an actual fight. $\endgroup$ Commented May 24, 2019 at 7:58

The monks are master swordsmen.

through: moving in one side and out of the other side of (an opening, channel, or location).

The monks know swordsmanship. To people who fight them (or actually people who have talked to people who have seen the monks fight), it seems as if armor and swords pose no barrier to the attacks of the monks. Their swords cut right through. If my offense comes through your defense, possibly I have shattered your defense. Or possibly, with my sweet monkish skills, I have sidestepped and bypassed your defenses and come through that way. As @Liam Morris points out, sword fighting is very much about skill; it is not just chopping down a tree (which also requires a modicum of skill).

The swords of the monks cut through steel defenses not because the monks are alien material scientists, but because they have such sweet martial arts skills.

The monks do not discourage the "magic sword" idea. They actually have some wild looking glass swords and other strange relics displayed in obvious places around the monastery. If you ask one of the monks about these swords, he will nod and smile.

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    $\begingroup$ Just to add to this, it is also possible that, as these monks are master swordsmen, there is no one alive to refute their claims as no one survives an encounter with them (or, if they do, they won’t survive against 5 more master swordsmen who are angry over their friend’s death). Furthermore, stabbing a sword through gaps in the armour, the eye slit of a helmet or even through chain mail and scale armour would, to your average person, appear as though the sword has been stabbed through the metal. continued. $\endgroup$ Commented May 23, 2019 at 12:34
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    $\begingroup$ In reality, you have only stabbed through the gaps, such as the eye slit in the helmet or where joints are. With chain mail, you are going into the gaps in the links and breaking them open, allowing the blade to hit the wearer. Even with scale, you are going into the gaps underneath the scales, not straight through them. $\endgroup$ Commented May 23, 2019 at 12:39
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    $\begingroup$ Maybe after the monks won what ever battle they we're fighting, they come along with sword cutters and cut swords to play a psychological game with the enemy to make it appear their swords can cut theirs. All the people who fought the monks are either dead or didn't go head to head with a monk. $\endgroup$ Commented May 23, 2019 at 23:35
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    $\begingroup$ @GrantDavis - then later when they are meditating they crack up thinking about it. $\endgroup$
    – Willk
    Commented May 24, 2019 at 0:14

You have another problem:

Suppose you had an infinitely sharp edge with no thickness: You still need to separate the molecules of steel from each other. This imposes a certain minimum energy per area cut.

Probably you can get a first-order approximation to this energy by looking at the power used by metal shaving equipment.

Suppose that it turns out to be 1000 joules per cm2 (Number picked out of my a... air.)

If your weapon weighs a 2kg, and you get it moving at 10m/s it has $\frac1 2 mv^2 = 100 J$ And so it would cut 1/10 of a square cm of steel -- roughly a 1 mm deep cut 2 cm long, with tapers at the ends.

I have zero faith in that 1000J/cm2 figure.

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    $\begingroup$ +1, the only answer which tries to evaluate if this is physically possible at all. Now we only need some real numbers. $\endgroup$
    – Michael
    Commented May 23, 2019 at 19:13
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    $\begingroup$ @Michael For steel, cutting energy is apparently in the range 2.7-9.3 J/cubic mm or 2.7-9.3 KJ per cubic cm. 1KJ was pretty good guess IMO. $\endgroup$ Commented May 24, 2019 at 2:52
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    $\begingroup$ Thanks. The 10m/s sword speed is a bit too low, apparently it’s more like 20m/s. But with the higher correct cutting energy it evens out. swordstem.com/2018/08/22/how-fast-do-swords-move-try-1 $\endgroup$
    – Michael
    Commented May 24, 2019 at 7:14
  • $\begingroup$ Hmm. I was only considering the energy to separate, and not consider the deformation. Separation should be a function of area, not volume. $\endgroup$ Commented May 24, 2019 at 14:40

Your problem is physics, not metallurgy. Steel is tough, even if your sword is perfectly rigid and takes no damage during a hit, you'll push the armor wearer back.

To puncture the armor, you need a lot of force concentrated in a very small spot, but then armor thickness of a plate mail is laid out to resist such stabs.

A much sharper material won't help you much since it won't improve the muscle power of the fighter. Lighter materials also don't help, since you actually want the weight of the blade to transfer momentum, and tougher materials also don't help, since that makes your blade prone to shattering.


A different framing challenge: why specifically swords?

@LiamMorris has given a really good framing challenge on whether steel swords could be cut so I want to give one on the idea of using a sword at all (or as the saying goes: "perception is reality")

In modern times, Unicorns invoke an image of a white horse with that spiral horn but early on people thought these were real creatures. It has been theorized that the myth and reality of unicorns came due to far-away or obscured views of giraffes and rhinos. Indeed, the term unicorn was also used to describe rhinos in Europe and in Japan the kirin キリン (Japanese for a mythical creature similar to the Unicorn) that was presented to the Emperor turned out to be a giraffe.

What does this have to do with swords? Nothing except that:

  • appearances can be deceiving
  • second hand accounts (esp. if based on a 1st hand account that was given by a person in shock) are not the most reliable
  • people who write histories (especially ancient ones) are not always 100% accurate

Use a club

So given the other referenced framing challenge and the other answers based on cutting steel: if we try to "cut" through a a steel sword it's just not going to work. However, if we have a blunt force weapon that looks like a sword, it has a chance to actually break (not cut) the sword. If an onlooker is:

  • Fighting his own battle and in a high adrenal (fight or flight) state & only catching glimpses
  • Staying far back to avoid getting drawn into the battle
  • Hiding under some kind of cover or concealment which can obstruct the view

and then sees our monk use his club to break the blade at all (even if just bends the blade or break means it knocks the blade from the tsuka or handle). There is a good chance he would think "Holy *@!*, did that guy just snap that other guy's sword in two with his own?!".

Add a few re-tellings and you have the "Legend of the Monk's blade which cuts through steel".

Japanese "Sword Breakers"

If there is a Japanese weapon, that already has a legend and nickname attached to them that relates to this it is the "sword breaker", the jitte or Jutte:.

Standard Jitte vs. Naeshi (no hook) Jitte

Standard Jitte - with or hook     Naeshi - Jitte without hook

With the above you could strike a katana1 and cause its blade to break or bend if:

  • it was cheaply made
  • had a defect
  • was not taken care of properly
    • damaged due to lack of skill
    • the tsuba not properly being attached after a cleaning
    • never cleaned because bandit doesn't know he needs to
  • other story reason here

History is fuzzy on if these were actually used to break swords but I've personally knocked the blade from the tsuba on a cheap (<$100) katana with my baton so I know it is at least possible that this had happened before2.

Or maybe these monks had contact with Europeans? The Bar Mace

Another excellent example, thank you Liam, is the Bar Mace (picture from "European Weapons And Armour" by Ewart Oakeshott):


Beyond the fact that someone seeing it from the side in action could be all like "What kinda crazy sword is that?!" due to edges, profile, and usage. The fact that this example is described by Ewart as an Italian example from the 13th century, would also add to the mystery as only the monks have a weapon like this (and maybe they occasionally speak this weird magic language using words like "pasta").

Then let the Legend grow

So all you would then need is someone to start telling the story of how they saw these monks fight these bandits armed with katanas (which are actually very cheap and/or poorly maintained but the peasant wouldn't be able to tell that), where one of them broke the bandits leader's sword into two pieces when he struck it with his own "sword". Soon the "telephone effect" will start and its turned into how he "cut the sword in two with his magic sword".

1: Note, with the hook variety: you would not catch the blade with the hook, rather you would block with the "blade" then hook the katana blade or, more likely and safer, catch the attacker's arm/wrist/cloths with the hook to apply control techniques. This is very likely the real reason they were named "sword breakers" they "broke" the sword's attack but the legend was attached and its basis in reality contested to this day.

2: It didn't even break the blade just knocked it from out of the tsuka (handle) due to it only being attached with a very small tang. Still heard people say the sword (blade) "broke in two" despite this fact.

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    $\begingroup$ Just to add to this, something like a bar mace (if it only had two edges and a point) could easily be mistaken for a sword, even at relatively close distances. You would only be able to tell it was a mace and not a sword if you looked at it up close with the edge facing you, then you would see it is far too thick to be a sword, theres no bladed edge, the weapon tapers in towards the hilt and not towards the point. From the side though, its profile would look like a sword, in fact it might look identical to a sword from the side. $\endgroup$ Commented May 24, 2019 at 19:04
  • $\begingroup$ @LiamMorris good point and I have a book with a picture of one - added. $\endgroup$ Commented May 25, 2019 at 0:03

As far as I know, no sword was really able to cut through metal armor. It's common in fiction, but probably even when shown on medieval drawings: it was an exaggeration to show the might of a king/famous knight and so on. Most of the cuts found on skeletons by archaeologists on old battlefield/post-battlefield mass graves are found on hands and legs since they were often not covered by armor.

You may find some YouTube videos showing cuts going through the armor, but they are executed on very thin, low-quality objects, being held stationary. In a real fight you would require so much force to cut through something that hard, that even if you had enough strength and sword that wouldn't break in the process, you would firstly push your opponent, since they wouldn't stand stationary, waiting for the sword to go through, force of the hit would push them (and probably also slide off from the initial point of impact), instead of pushing blade through the layers of steel.

Swords breaking on each other were a thing, but doing so on purpose not so much. Especially that again: if something is pushing at your blade strong enough to break it, your hands will bend or break first.

So: I don't think you can find any historical precedent or very down to earth justification of something like that occurring. You will need some magical mumbo-jumbo, but it probably should contain a mix of superhuman speed, so cut goes through faster than body/sword is able to move out of the way, that would force sword to go into the armor instead of pushing target away and amazingly hard steel (that would also make it preserve its sharpness), so it won't break or shatter in the process. And, because the blade slides off the target whenever it can (seeking for the path of least resistance), a fighter would have to land cuts on ideal angles, so the blade won't end up laying flat/sliding off.


Let us take an example perfect edge. An edge is a mathematical line, at the intersection of two planes or curves. The perfect edge is perfectly straight and perfectly thin, that is, with zero width. Any deviations from straightness or thinness make it worse at cutting.

An atom is the thinnest width that a physical edge made of atoms can have. That's at the atomic scale. A medieval sword might be a million atoms across or worse, with a broad, blunt edge pressing and scraping across whatever you want cut. Already we are losing cutting ability.

The perfect edge is made of perfectly strong material that never wears away (chips, burrs, or cracks). In the real world, it must be made of atoms, which have bonds of limited strength to their neighbors. When that bond's strength is overcome, the atom is ripped away or shoved away from the line, distorting the straight edge. Chips, burrs, and cracks appear in the line. We are losing more cutting ability.

If you want to cut through steel armor (or another sword), you would need a very thin, unbreakable line for the edge. In science fiction, Larry Niven's Variable Sword is appropriate. The Variable Sword is a handle, a little glowing button to show the end, and between them an invisibly thin unbreakable stiff thread. It wielder cuts through most objects without effort.

A real-world sword is made of atoms, which support each other and form the 99.9% of the sword that isn't edge. (99.999999...) The atoms must be bonded together so that the sword doesn't wear away quickly. But materials have several different measures of "strength": compressive strength, tensile strength, hardness, how far the shape can bend and still return to its original shape, etc. The melting point is important, too, as well as characteristics as the solid heats up, because a hot sword is easier to bend.

Medieval crafters don't have the materials science to define good steel, let alone create good steel, let alone create a large amount of good steel repeatedly. If they somehow got their hands on an excellent non-steel material, they would have a very hard time putting into the shape of a sword, let alone putting an edge on it.

Let's imagine they isolated ten pounds of tungsten (it's almost thrice the density of iron). They would need the materials science to make a ceramic mold that could withstand its tremendous melting temperature. That makes a sword-shaped object with a blunt edge, and they have to put tremendous amounts of time and effort into sharpening it. And still, its edge would be a million atoms across, and still, using it blunts the edge.

Other very hard elemental metals have similar problems. Some of them are quite toxic as well.

Let's imagine they acquired a sword that is a single crystal of diamond. Nice and light, but it will chip and shatter easily. Also, the carbon gets absorbed into iron and steel it presses into, so the edge will quickly be ruined.

Long story short - steel is used for swords because it's the best compromise known of all the problems known. A society needs science to be able to define better materials. Better materials are frequently just more-precisely-understood steel with vanadium, tungsten, molybdenum, etc. And it's still not going to cut through armor or other swords without blunting.


Steel is not a simple thing, it can be engineered to have a range of different properties, and in fact, many of the tools used to work with steel are made from different kinds of steel, e.g. tool steels https://en.wikipedia.org/wiki/Tool_steel and high-speed steels https://en.wikipedia.org/wiki/High-speed_steel

To make plate armor, you'd instead want relatively malleable steel that could be beaten into shape. Thus a sword (say a Japanese katana) made from hard & tough steel could cut the armor if wielded with sufficient force. Likewise, if the other people's swords are made of such steel (because they don't know the secrets of the "magic" steel), then it might well cut a sword used for parrying. Though that would really be an inferior technique...

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    $\begingroup$ 'Sufficient force' seems to be the bigger problem then steel quality, actually. Steel is objectively a good material for armour and, especially, weapons. Even if you had a sword with an edge made of modern compounds that are used in armor-piercing bullets, it will not be able to cut steel weapons as butter. $\endgroup$
    – Cumehtar
    Commented May 23, 2019 at 8:19
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    $\begingroup$ Katana cutting armor is a myth, A katana a will shatter before produces in cut in quality armor. Traditional Katana may be hard steel but they are anything but tough. $\endgroup$
    – John
    Commented May 23, 2019 at 13:37
  • $\begingroup$ The Katana design is excellent, but don't forget why they had to harden their steel. It was inferior iron that they had to work with when compared to European iron. $\endgroup$ Commented May 23, 2019 at 14:11
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    $\begingroup$ @jamesqf, when cutting steel with a tool, you concentrate a lot of power in small area. When cutting something with a sword, the area of contact is actually significant, and sword tries sliding on armor, even if the sword edge is harder then the armor surface. (Instead of applying your chisel to the steel plate that lays on the bench, make your friend hold the plate and try stabbing it with a chisel). That is why after 13th century most of the swords become thrust-oriented. I can understand swords from superior metal defeat steel armor by thrusting, but not by cutting. $\endgroup$
    – Cumehtar
    Commented May 23, 2019 at 17:53
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    $\begingroup$ @Luaan: Of course the ability something to cut depends on the proper angle - I've often had an axe glance off soft pine wood, for instance. The point of armor seems to be to deflect the many glancing blows. The sword cutting armor wouldn't be a normal thing, but something that possibly could happen if the angle is just right. $\endgroup$
    – jamesqf
    Commented May 24, 2019 at 16:33

I don't know how SuperTech you wanna go, but if you want something lightsaber-ish but not a lightsaber, you could have a very thin ceramic heating element, heated up to around 10eV (115,000 K), not a sword, but a very very Hot... Rod.

OK, so your HotRod emits blackbody radiation at a peak of several eV (hard i.e. ionizing UV and soft x-ray) so it doesn't glow in the visible spectrum, but it will ionize and thermally excite air out to some distance. Depending on how hot you want the HotRod to be, this glow could be confined to a few mm from the rod (lightsaber-ish) or it could be spread around a 10 m radius sphere (The monk appears cloaked in a nimbus of strange and whirling lights.) The Monk wielding it is definitely going to eat some Rads, but 1) Monks are already head-shaven, 2) Monks might have a vow of chastity (don't start the HotRod next to yer jimmies!!!) and 3) Monks might have some advanced medical tech or secret herbal tea that heals radiation. A captured HotRod is effectively a cursed item to a non-monk, who promptly contracts a strange wasting disease upon playing with his monk-toy...

OK, so what happens to a struck sword? Assume a straight-bladed sword with a diamond-shaped cross-section 3cm x ½cm, and the strike affects 1.33 cm of blade length (this works out to 1 cc) with the steel blade having a density of 10 g/cc (high for steel, which is ~8), a thermal conductivity of 50 W/mK and a specific heat capacity of 500 J/kgK (All of these are reasonable numbers, Thanks Google!). When the 1 cc of steel blade comes into contact with the HotRod at 115,000K, it will suck heat at a rate that will change its temperature by 34,200 K/s. After 50 ms of contact (basically instantaneous as far as human reflexes are concerned), the assumed volume of steel blade in contact with the HotRod will heat up by 1710K, from a starting point of, presumably, 290K (room Temp), this means that the portion of the blade struck will be 2000K after a twentieth of a second, and steel melts at 1650K. So your HotRod just turned a portion of steel blade into slag, with 1 solid portion falling away and the other still attached to the handle, it's medieval owner looking like a sap...

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    $\begingroup$ At 115 kK, you'll probably still have plenty of energy over the visible spectrum. Total power increases with the 4th power of absolute temperature, so there's an absolutely ridiculous amount of total power, plenty for there to be a visible amount in the visible spectrum even thought most of the power is at shorter wavelengths. (Unless the blackbody emissivity of the material is extremely low. Which would actually be necessary for it not to simply cook anyone near an object as large as a sword blade, nevermind the ionizing radiation.) $\endgroup$ Commented May 25, 2019 at 18:24
  • $\begingroup$ Peter, thanks for your comment and upvote! I did not want to deal with emissivity, so I hand waved that as either a glowing rod or a nimbus of light out to several m, but yeah, you are right, the thing will light up like a dead tree on xmas (10^13 W/m² -- Ouch!). OOH! Maybe the material has a low emissivity for EM but converts thermal energy into Phonons at a distinctively low hum.... (lightsaber-ish, I know....) $\endgroup$
    – Dude707
    Commented May 28, 2019 at 17:56

Your monks, through going into battle with a pre-wound motor, are now able to make their blades vibrate at the right frequency to have the motion do the cutting, not whacking the blade (it is now a very fast saw). If they are advanced scientifically, they can make a motor with an uneven weight on the end, powered by a rotational spring (or spool of string for short engagements).

Some drawbacks:

  1. It will not cut through like nothing is there. You have created a saw, not a lightsaber.

  2. Vibrating motion, for an extended period of time, will number their hands, or at least be uncomfortable. They may be able to withstand this through monk discipline.

  3. It would not work for extended engagements where many strikes are needed, as your motor would run out of preload.

  4. The blades would have to be thinner than normal blades. This would make them more brittle unless your monks are better at treating steel.

I don't know how realistic you want this to be, but maybe these monks offer up a special prayer to Combat God, and use the power granted to vibrate swords for an extended period of time. Although, at that point, you might as well have them pray for a lightsaber.

  • $\begingroup$ Maybe they use a rapier... $\endgroup$
    – Efialtes
    Commented Jun 5, 2019 at 18:05

You are after the old-style Damascus blades made from Wootz steel.

To make a long story short, about 2000 years ago a certain type of steel came out of India known as damascus steel (not to be confused with modern damascus). This steel was renowned as far stronger, held an edge longer, and handled flexion better. You can read about it on Wikipedia.

It was known to be able to cut through other steel, shear stone without blunting and had a recognizable pattern across each blade.

Essentially the art of making it was lost as the blacksmiths died and modern attempts to recreate it have failed. Although in examining the blades modern science has uncovered carbon nanotubes inside them, (carbon nanotubes are approximately 100x stronger than steel and harder than diamond) which is incredible as carbon nanotubes are a relatively recent scientific discovery.

I feel like you could quite easily incorporate this type of steel into your world and the real world story behind it fits in very well with what you are trying to create. Sorry that I don't have more details but a google search should provide them.

The main thing is not to confuse modern damascus steel with the historic version. Modern damascus steel is just pattern-welded steel to try to recreate the pattern, and while it can sometimes be stronger than other steel, it does not bear the same properties as the historic version.

Here is another article on it.

  • 4
    $\begingroup$ That's not quite correct. Damascus steel was certainly very good for its time, but that doesn't mean it is better than blades created with modern metallurgy - nor, crucially, that the legends about it are actually correct. :) Whilst the process to create new Damascus steel was lost, the weapons themselves are very much still around. Western metallurgists did have an opportunity to study this steel before the technique was lost, and it formed the basis for developing high-carbon steel. $\endgroup$
    – Graham
    Commented May 24, 2019 at 12:18
  • 2
    $\begingroup$ "A research team in Germany published a report in 2006 revealing nanowires and carbon nanotubes in a blade forged from Damascus steel." +1 $\endgroup$
    – Mazura
    Commented May 25, 2019 at 19:42

There are some wonderful answers here, mostly explaining that steel sword on steel sword is a tough nut to crack because of good ol' physics and metallurgy. There is another way to do it though....we can cheat with the power of narrative convenience and swipe some ideas from old sci-fi stories.

Your Monks will, of course, come from Shambala or some other mystical mountain fastness. It always has perfect weather, just the right kind to make things grow, to ward off violent storms, and so on. This is because it is the home to the Legendary Quantum Weather Butterfly (Thank you Sir Terry Pratchett) This butterfly can alter the weather by flapping its wings this way or that way because the edge of its wings is fractal, and therefore infinitely long. The good weather is only a bonus though. The real key is the silk produced by the caterpillars that eventually become the mature Quantum Weather Butterfly.

The interesting thing about this silk is that it is not just really fine, but that each strand is, in fact, mono-molecular. The real skill these monks have is not in making steel (they aren't slouches though), but in being able to handle the raw silk and using it effectively.

What the monks do is craft a mediocre steel sword with blunt edges. Then they wind the silk around the tip and the handguard. They then run a single strand from tip to guard, getting it as taut as they can maybe as much as 1mm away from the actual blunt edge of the blade. Given that the strand is one continuous molecule, it will have the same strength as the bonds between its individual atoms, so the thread itself is nearly indestructible by normal means. Also, since it is only one molecule thick, it will be able to cut through just about anything like a wire through a block of cheese.

Anyone observing these blades in action will be astounded at how they seem to shear through inferior steel weapons and armor. The cut will seem to begin slightly before the blade makes contact with whatever when seen up close.

The second point is that through their martial arts training, they are actually going to be striking the enemy weapons weakest points. The haft of the spear or mace, the handle of the axe or sword, the straps or joints of the armor.

The swords themselves will probably have significant wear after a handful of battles. but will just need to be rewound with fresh silk.

So the monks provide a safe place for the butterflies, and the butterflies give the monks awe-inspiring weapons, cool clothes, and the kind of weather where you don't mind not having hair.


In reality, you cannot break a sword with a sword, and it very hard to pierce armour with one. With some reasonable metallurgy skills and a design which is essentially a club with one sharp side, you could likely break some swords and smash some armour, and you would not really have to keep it sharp since it is basically a blunt force weapon. You could make it superficially resemble a sword and the monks could spread rumours that the club is a sword.










The thing to remember when we attempt to answer this question isn’t can they break a sword? Because we have them doing that on camera, and a verity of other similarly impressive feats on tape. They usually break swords with there head. I found the guy who was bending and deforming high grade stainless steel with his kicks to be highly impressive. What we are looking for is something less like a sword and more like... the worlds least destructible metal, (mythril, adamantium) and what shape does that need to be... to allow them to focus that energy. We need a thing to focus energy. Cause their head, wrists, fingers, palms, They diffuse and spread the energy out over a wide surface area. Cause the guy who is practically kicking socket wrenches in half. He’s already applying sufficient “un-focused” energy to cut it in half. The guy who can throw a needle thru glass, the guy who can cut a B.B. in half fired out of b.b. gun. With a katana, The guy who can smash a rock by poking it with two fingers. The guy who can smash 4 bricks by slapping them. These are feats they can actually do, in modern times and by people of a high skill level for them, but not the highest. It then becomes very reasonable to think a supremely gifted natural prodigy in ancient times would very much be able to destroy a sword, rather easily by smashing it with his head. He can do it. There is no problem with his ability to do this. Our question is with all the massive amount of knowledge at OUR disposal can we craft something that is sufficiently close enough to +3 enchanted dwarven mythril to withstand the force and energy this monk is going to channel thru it. His ability to focus the energy is just fine. I think we need to think less along the lines of a sword and more along the lines of a metal bar that looks sufficiently like a sword, has similar properties and proportions and may well be able to perform the same functions as a sword, this is still less a sword and more of indestructible metal bar. It’s functional in the sword regard perhaps, but were thinking more along the line of physics, rules of motion simple machines, ect. I think the monks are keenly aware of these things. In particular i think there keenly aware of the limitations of there physical body which they have turned into a living weapon. We don’t as people have “edges” that would make for the ideal transfer of focused energy to the blade. They can still break blades with there head and such, but once you equip them with an indestructible edge, that they can channel their energy and force thru. The question is can WE make that. Scientifically, what is the best, metal, shape and forging process that would allow the monk to focus the energy into a specific place. Cause that should break the sword. And if not then he will head butt it and break it. HE can do it. Can we put the thing in his hand that works better then his skull? all we have to do is better then his skull. But if we fail, we fail. This guy can already break swords without out help. Can we give him a tool to help him break a blade better then can with his own skull. We just have to beat or do better then a skull. He’s already breaking blades just fine without the aid of a tool. Can we create for him a tool or are WE inferior. Because he has ancient eastern martial arts abilities that allow him to break swords. Without us. He’s already doing it with just his body. If we can’t use modern science to make a tool that can help him do it better that doesn’t mean HE can’t do it. Were just failures in creating a tool. The monk is already able to do this without OUR help. Food for thought. Also i am believing the angle of a bandit with a poor sword. I don’t think any bandit would have much luck against a monk of the highest skill level amongst all the temples of that region. Grand masters would have been un assailable against people who weren’t trained from birth to compete against people of that skill level. They would literally be a chump holding up a thing for the monk to break. It’s not like a life or death battle at that point. It really is something like want to see something more impressive then break your sword with my head? Sword destroyed by metal bar. They generate the energy needed for doing this. It’s the object in his hand to deliver that energy into a small, thin, surface area that needs the work. Imagine they CAN do it. What do you give them to do it better? :) enter image description here


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