On a future battlefield where mechs are somehow the most preferred weapon system (over the far more practical tank format), what kind of melee weapon is most effective?

From human warfare, we see the evolution of weapons from swords to morning stars to hammers. The reason for the evolution in weapons is that swords became less and less effective against plate armor over time while concussive hits by hammers proved to be incredibly effective. (Then there were guns but that's outside the scope of this question.)

Does this evolution hold true for giant bipedal armored combatants? Would an apropriately sized hammer be more effective in melee combat between mechs than a giant sword? If this does not hold, then why not?

The mechs in question range in size from 5 meters tall to 20 meters tall and 6 tons to 100 tons.

Based on this question about why mechs would use melee weapons over ranged weapons.

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    $\begingroup$ swords only work becasue the target is relatively soft compared to the sword, as a cutting weapon an axe might work becasue the cutting edge is more concentrated, although it is still largely bludgeoning. there is a reason demolition axes and demolition hammers exist but not demolition swords. $\endgroup$ – John Jan 6 '18 at 16:04
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    $\begingroup$ If you are in melee combat in mechanized vehicles things have gone horribly wrong.... $\endgroup$ – Thucydides Jan 6 '18 at 16:07
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    $\begingroup$ @TheMattbat999 no it really won't swords do not pierce metal armor they go around it, which is not an option for something made entirely of metal. . $\endgroup$ – John Jan 6 '18 at 19:27
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    $\begingroup$ This isn't an answer to the question but I feel garners mentioning; Bipedal mechs suck for combat purposes. There are a lot of reasons and in combination with another user I have written out some reasons why worldbuilding.stackexchange.com/a/10325/45157 worldbuilding.stackexchange.com/a/99030/45157 if you have already established bipedal mechs these points may give you some modifications you can make or the next technological advancement in the story. $\endgroup$ – BornToDoStuff Jan 8 '18 at 15:17
  • $\begingroup$ If Robot Wars has taught us anything, surely it's a giant spinning disc that you need! But seriously, why all this talk of swords and hammers? I would have thought - if it has to be melee combat - our mech would be using precise but fast moving cutting weapons like rotary saws and drills? $\endgroup$ – colmde Jan 9 '18 at 8:55

11 Answers 11


The real problem with martial weapons is materials.

A steel sword vs leather armor is effective. A steel sword vs steel plate... Not so much.

The driving factor is that both weapon and armor will deform on impact. What you're designing for is to have the one that deforms last.

The easiest ways to ensure that you win in the collision, is to add mass and carefully design the geometry to shape the forces of the collision to your favor.

Weapons have the advantage of getting to chose where to apply the force of impact. The wielder gets to choose the point that of impact where the armor is weakest.

For a mech, the weak points are similar to a person in plate armor: the joints. Aiming a sword into the crack of a join to muck up the workings inside requires speed and accuracy. But you don't have to get inside to stop a joint.

You can bend it just enough it can't move.

Enter: mass weapons, i.e. Hammers.

Beat on the joints till you break something, or bend it enough to stop moving. In modern armor combat, this is called a mobility kill.

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    $\begingroup$ Hammers and smashing weapons like maces were designed to deliver a blow which cold crush or penetrate plate armour, so in theory you could strike anywhere with a hammer and deal injury. Once plate armour became common, swords evolved into the rapier form, for rapid thrusts into the gaps and joints of armour plating. The two forms of combat are quite different as well, a Mech swinging a hammer will be "effective" while a Mech designed to use a rapier like sword would have to be very fast and agile. $\endgroup$ – Thucydides Jan 6 '18 at 21:50
  • $\begingroup$ As an aside, non-metal armors are much more effective as protection against swords than popular culture lends one to believe: Although only-leather armor was almost unheard of, effective protection can be made even from linen: cf. gambesons $\endgroup$ – errantlinguist Jan 6 '18 at 22:34
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    $\begingroup$ I’m not convinced that swords are ineffective against steel plate. In fact, I distinctly remember this not being the case in empirical tests (and it’s more than plausible, given the physics of edged weapons): steel plates were only ever designed to, and useful against, deflecting glancing blows. Not full-on hits. So, do you have a citation to back up this claim? $\endgroup$ – Konrad Rudolph Jan 6 '18 at 23:56
  • $\begingroup$ I'm not saying one is better than the other, just that they face the problem in different ways $\endgroup$ – Stephan Jan 7 '18 at 2:49
  • $\begingroup$ Give your hammer a small surface feature like this to have the best chance of deformation goo.gl/images/k8Ndhn $\endgroup$ – bendl Jan 9 '18 at 13:37

Your mech should use a hammer, but not a sledgehammer that it swings around with its arms. That is the best humans can do but you can use tech to store energy and then release a tremendous amount with each blow.

The hammer should be a pneumatic or hydraulic hammer: it will store energy as pressure then release it with the impact. Hammers like these (jackhammers being a good example) are routinely used for demolition. A jackhammer releases the energy as multiple small hits but you could release it with one big hit.

You hammer will need to restore pressure after each hit. I am a little worried about a "dry fire" - if the hammer piston does not impact anything before reaching the end of its length the energy will need to be absorbed by the hammer housing which is less than ideal. You could have some braking mechanisms, ideally regenerative to capture this energy in recompressing your working fluid. Or you could side step this (perhaps in an ad hoc manner!) by untethering your piston and allowing it to continue completely out of the hammer. It might impact something farther away. You could retrieve it later if things go well.

  • $\begingroup$ If you're willing to sacrifice energy to control momentum, you could fire hammers in opposite directions to cancel out momentum, which would simplify the process of arresting the hammer hit. $\endgroup$ – Cort Ammon Jan 8 '18 at 21:10
  • $\begingroup$ @Cort Ammon - these mechs would jockey for position for hours, trying to get between 2 enemies so they could fire both hammers. $\endgroup$ – Willk Feb 16 '18 at 2:21

People have already suggested hammers so I think I'll take an alternate tact.


Hammers are tremendous weapons for inflicting huge, crushing blows on enemies. Unfortunately, they are slow and unwieldy compared to many other melee weapons. What you can't hit you can't hurt, and the downside to swinging large masses around is that, given a miss, there is still a lot of momentum carrying on. If the goal is to limit the mobility of your opponent, spear weapons can make a lot of sense. Spears allow you to thrust quickly, to concentrate a huge amount of force on a very fine point, and to do so without over-extending yourself and opening up to a counter strike.

Tweaks for Mech Combat

Furthermore, a spear can be more than a spear. Depending on your rational for melee-exclusive combat, a spear can act as a delivery system for more advanced weaponry. A spear could pierce a Dunesque Holtzman-Effect shield and then deliver an explosive or plasma charge. A spear could pierce the electrical shielding on the outside of a mech in order to deliver a debilitating shock, a jet of conductive or acidic liquid, expanding foam, or hell even a computer virus (injecting code indeed).

These type of attacks would lend even more safety to spearfighting, as the strikes could be made with very little force, quick, darting jabs that are accurate and easy to retract.

Harpoon Style

Furthermore, it may be a good tactic to use a harpoon. With a classic Whaling Harpoon, you could stab your enemy with a weapon that would be difficult or impossible to remove. Thus, you could keep hold of the weapon and use it to pull the enemy off balance, or you could let it go and have its weight, damage, and overall unwieldiness hamper your enemy while you draw another spear to finish them off safely. With a hooked harpoon, you could disarm your enemy, catch then with the hook part and pull them off balance, or pull down their shield if they carry one.


Spears are simple, adaptable, and deadly weapons. They are easy to use and have a high skill ceiling. They allow your soldiers to maintain distance while in combat, keeping them safe. Mechs equipped with spears could even fight in formation. Hammers are great and all but they have very significant drawbacks; There is a reason why spears are the weapon of choice for infantrymen for most of human history.

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    $\begingroup$ I really like the expanding foam spear idea. That is a really unique and actually pretty plausible angle on using an ancient weapon in a new creative way given the larger size it would be crafted at. $\endgroup$ – BornToDoStuff Jan 8 '18 at 15:25
  • $\begingroup$ @BornToDoStuf Yeah, I was thinking about what would be different between mech combat and normal human combat. That was one of the spots I thought might allow for some ingenuity. I'm also thinking the speed at which mechs might be able to move would be very important, so carrying something heavy like hammer didn't make a ton of sense for me. $\endgroup$ – Dent7777 Jan 8 '18 at 15:43
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    $\begingroup$ Not just spears, but polearms in their various forms. A Halberd has a stabbing point, and axe blade and a hook all incorporated at the end of a long pole for leverage, for example. Of course you can get a funny picture of mechs formed up in a pike square with 100' long sarissa's in hand..... $\endgroup$ – Thucydides Jan 8 '18 at 16:35
  • $\begingroup$ @Thucydides Yeah, I feel like polearms definitely would have a place depending on the situation. I was just writing my answer with urban combat in mind. I guess I assumed that, no matter the handwaving, tanks and traditional vehicles would be used for combat in the open field, and that whatever protected the mechs wouldn't protect them from an orbital strike or bombing run or artillery hit. $\endgroup$ – Dent7777 Jan 8 '18 at 16:48
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    $\begingroup$ I wish I could up vote this more. Spears really are the best option here. Make the point out of something really hard like tungsten and you've got a winner $\endgroup$ – bendl Jan 9 '18 at 13:29

Definitely hammers

Hammers do a lot more damage over a greater area allowing for less accuracy being needed with them than with swords. Plus Hammers can have one side that can be pointed allowing for piercing if it is needed, but swords cannot have this dual functionality.

But swords do have some upsides when compared to hammers, especially sledgehammers. Swords aren't as heavy and are more precise on targets and are faster than hammers. But when compared with all the damage hammers can do and the fact that your fighting with big metal monster machines, a hammer, especially a sledgehammer is better for those types of battles.

Also a good reason for using melee weapons is that they last longer and you don't have to sore a bunch of projectiles to use your weapon. Or you could say it's a cultural style to fight like that, just like how the British used formation in the American Revolutionary War battles partially due to culture and how the Europeans fought.

  • $\begingroup$ "Hammers do a lot more damage over a greater area", not entirely true, sure a hammer can hit more places at once (surface area) but the damage it does is directly proportional to how much force is applied. Hitting larger targets with the same force will minimize the impact of the hammer. $\endgroup$ – Jason Bristol Jan 6 '18 at 19:03
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    $\begingroup$ @JasonBristol yes but these are giant mechs were talking about so strength is a given and not really a problem. $\endgroup$ – Amoeba Jan 6 '18 at 19:28
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    $\begingroup$ Jason's right there is a reason war hammers are not flat, they are pointed or finned to concentrate the force, maces are even better. $\endgroup$ – John Jan 6 '18 at 19:29
  • $\begingroup$ @John but those war hammers were for killing humans, these are mechs, giant killing, shelled machines. It's like they would be good at dispersing kinetic energy which would seriously destroy the effectiveness of the lance or sword but a hammer would get the others off balance and break up the surroundings to make the terrane rougher and destroy the foundations of large objects to make them fall on the other mech $\endgroup$ – Amoeba Jan 6 '18 at 19:39
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    $\begingroup$ @user45751 You do not break large objects or terrain with large flat hammers. Usually something like a pickaxe. Warhammers were non-flat to effectively bypass armor. $\endgroup$ – Revolver_Ocelot Jan 6 '18 at 20:33

So the question here is can you make a sword out of a material hard enough to penetrate the mech's armor.

Hammers, as effective as they are, are not quite the weapons they appear to be on paper. Sure the concussive force they apply is great, and it's very hard to protect against them, but have you ever used a sledgehammer before? Hammers aren't exactly fast, and a bad swing will leave you open and possibly even off balance. You also have the problem of range because there is a very specific distance that the hammer will be effective from. Any closer than that and its next to useless.

A sword's biggest problem is penetration, as you mentioned. However, swords do carry pretty significant amounts of kinetic energy themselves. Get hit with a wooden training sword and see how easy it is to just walk it off, (spoilers, it's not). Also, you are talking about mechs here, a sword that big will be very heavy, and if your mech can swing it fast enough to use as a sword then every hit will have a lot of force behind it. Unlike a hammer, the distribution of mass on a sword makes it much easier to swing and recover from, and you are less likely to be put off balance as long as the blade isn't ridiculously huge. A sword is able to do a number of jobs, from slashing, slicing, stabbing, and yes, even bludgeoning. However, swords also take more skill that most weapons to wield effectively. The reason samurai were so feared is because they were incredibly hard to beat in one on one combat, and the reason they were comparatively rare is because it took years to train them to that level of skill.

So with that in mind, it's a question of skill and material. More skill and higher quality materials, sword. Less time to train and lower quality materials, hammer.

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    $\begingroup$ Isn't the Samurai thing is more about people romanticizing them more than anything else? Good Iron and Steel was very hard to come by in Japan unlike in Europe, meaning a fully equipped Samurai was already super rare even among the rich. They weren't able to afford full metal armor either and their swords were designed to cut flesh not metal, while Europe had much more iron, so every noble and their guards had a set of armor and a sword designed to pierce that armor. $\endgroup$ – Shadowzee Jan 8 '18 at 2:26
  • $\begingroup$ Once your armor is strong enough, a sword would only be able to slice at the joints or pierce the armor using its tip. A hammer would instead impact a high amount of force on the armor itself, which would be transferred to whoever is inside it, so you wouldn't need to pierce the armor to do damage. $\endgroup$ – Shadowzee Jan 8 '18 at 2:28
  • $\begingroup$ A lot of the samurai armor was ceramic though, which is fantastic against cuts but bad against impact, well the 2nd impact. Samurai trained to aim for weak points though, like the neck, elbow, knees, and under the arm. You are $\endgroup$ – Nick Jan 8 '18 at 2:30
  • $\begingroup$ Sorry cut off my comment, you’re right about romanticizing, but with literal years of constant sword training it becomes very hard to actually defeat a swordsman one on one. The big problem is time and training, as it takes much less time to train a soldier to use spears or hammers. $\endgroup$ – Nick Jan 8 '18 at 2:33
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    $\begingroup$ That is true, in most cases a hammer will be the best option. A big part of this depends on the mech design though. If it replicates the human’s movements pretty much perfectly and you put a master swordsman in the cockpit, they will have a speed and versatility advantage over a hammer. So they will land hits pretty much whenever and wherever they want, while the hammer will be too slow to keep up. However combat is constantly changing, so relying on a single weapon is normally not very wise. Like all combat it mostly boils down to the individual person far more than the weapon. $\endgroup$ – Nick Jan 8 '18 at 3:01

I think most people are focusing on swords for slashing and neglecting the stabbing option they bring. People also are focusing too much on the comparison between mech and plate armour on a person. On a person, chop off an arm and the fight is decidedly over. But with a mech pain and blood loss isn't a problem.

Commonly in mech design there is a glass cockpit for the driver to see out of. Even if not glass it would be thinner metal. A rapier type sword could be incredibly effective at poking the driver from range in a spot that's quite vulnerable to it. A rapier can maintain distance from a hammer easily and effectively attack the weakest point of the mech, the driver. It can also be used to poke at the joints, and while a human wielding a rapier against plate armour isn't very effective, keep in mind a mech would have a ton more force behind it.

Sword techniques also developed to combat armour, such as bashing with the hilt.

I think primarily the rapier on driver strategy is the best tactic, but that using the sword to stab at joints would work well, and the mechs could even have the strength to chop off parts with a sword.

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    $\begingroup$ Why on earth would you not bury the driver deep within the mech and use technology to give a view of the battlefield using cameras and sensors. There is NO reason to leave the driver so exposed in a technologically advanced situation, especially if the combat is oriented towards large melee weapons and bashing/stabbing at the only human component, the driver. Saying a rapier can stay out of range is also assuming that you cant just make a longer hammer. Mechs aren't restricted by human limitations so they could use longer shafts. Rapiers however are more mechanically limited by material. $\endgroup$ – BornToDoStuff Jan 8 '18 at 15:20
  • $\begingroup$ My argument included a non-glass cockpit. But given that it would need to be an empty cavity it would still be weaker than solid metal. Also I'd posit any relative length you can add to a mech hammer you could also add to a mech rapier. It would be a comparably thick rapier, but that wouldn't have to hurt it's effectiveness, some rapiers are shaped like a cone that comes to a point to add thickness to the base and gradually come to a point. Would be good for making a long rapier. $\endgroup$ – Centimane Jan 8 '18 at 15:42
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    $\begingroup$ I feel like at that point you are just using a spear which is cheaper and easier to make. $\endgroup$ – BornToDoStuff Jan 8 '18 at 15:54
  • $\begingroup$ Pretty similar in effect, but the post is specifically sword vs hammer. $\endgroup$ – Centimane Jan 8 '18 at 17:01
  • $\begingroup$ "Weaker than solid metal" is a relative statement. And not always true. You can drill circular holes into the vertical plane of an I-beam all day long and not really affect its overall strength (but reduce the weight significantly). The same goes for a spherical bubble within a solid metal object: the stress curves around the void and is distributed away without issue. And that's assuming that the mech as a whole is "solid metal" which is also not true: there's joints, hydraulics, electronics, and other systems contained within that affect the "bending strength" of the whole. $\endgroup$ – Draco18s no longer trusts SE Jan 8 '18 at 20:47

You might want to take a look at Front Mission's "Pile Bunker":



A hand mounted pneumatic spike that gets released quickly with some type of gas. It would be more effective than either a hammer or a sword for mechs as it would release a great thrusting force over a small area, which makes for a very effective pierce. It's not as flashy as a hammer or a sword, but it's certainly more effective.

In fact, even a giant metal baseball bat would be more effective than a sword in a battle of mechs. Because the sword is made for cutting. However, a giant mech is probably made of a very thick metal armor. A giant sword would, at best, only make a notch in the armor. That's without taking into consideration a mech's armor might be sloped, making it harder to land a propper blow, not to mention the body itself moving around, further reducing the cutting power of an incoming blade.

Using a giant bludgeon, you wouldn't focus on cutting, instead on transferring the full force of the blow onto a mech. Much less chance of a glancing blow, with more force transferred with the blow and with the same handleability as a sword.


OK, while giant mechs are silly, there are some memes which will not die. Space fighters is another one.

So, in order to destroy or cripple an enemy mechanized vehicle, which is presumably armoured like a tank, with a physical blow would require a very large and fast moving object to strike it. (edit: to put this in perspective a 105mm APDS projectile [common on 1960 era tanks] struck with 13 million foot pounds of energy). A lot of momentum is going to be generated by the fast moving object, and if you hit, the momentum is abruptly stopped, with some adverse consequences for the person or machine swinging the object. If you miss, the momentum will likely carry you past the object you swung at, which is also not a great thing when involved in hand to hand combat.

So what you want is something which can dissipate the striking energy in a way which is not detrimental to the mech doing the strike. I would suggest a flail or chain weapon.

enter image description here

war flail

Now there were lots of variations, but the essential thing is the striking head(s) is attached by a short chain to the handle. The full force of the impact is not being directly transmitted back to you, and a return stroke is much easier than with a solid weapon like a war hammer or pole arm. The chain is also versatile enough to be used to entangle the opposing mech's limbs, and the weapon can be reversed and the handle used as a bludgeon if needed.

Of course, if you are really that close, then you are in pistol range. A mech could have the equivalent of a giant claymore mine strapped to the chest armour to detonate when close to an enemy mech.

Or you can just call your space fighters down to strafe them.....

enter image description here

This is how you deal with mechs

  • $\begingroup$ Close Air Support is one of the scariest and best missions there is. +1 for pointing it out. $\endgroup$ – Green Jan 8 '18 at 22:05

TL;DR combine the best of both (or make a giant halberd, possibly).

A "sword" on the scale you could carry on a mech is not the same beast as a hand-held one. It needn't even be especially sharp. If you go for a nice solid square or diamond cross-section you'll have two or four somewhat-pointy edges and can deliver what amounts to a hammer-blow, but slightly more focussed.

Another way to look at it, is how can you make a hammer a bit longer (targetting has a little more leeway) and pointy (for those attacks on the enemy mech's joints, power conduits, hydraulics etc.).

Edit: I'd overlooked @John's comment on war hammers being made pointy. No stealing intended!

  • $\begingroup$ Also, imagine giant mechanoids fighting with the equivalent of quarterstaves, à la Robin and John Little :o) $\endgroup$ – Will Crawford Jan 8 '18 at 12:26
  • $\begingroup$ If we are going to come up with melee weapons on that scale, then swinging a giant chain would work as well. The impact of the chain would replicate a medieval flail, while the chain itself can entangle limbs and bring the enemy mech down. Sweeping a chain into a building can also destroy the building, clear out enemy infantry etc. OTOH we really should be asking "Why not just shoot the guy?" As far back as the American Civil War, only a small percentage of battlefield injuries were inflicted with edged weapons like bayonets or swords. $\endgroup$ – Thucydides Jan 8 '18 at 21:04
  • $\begingroup$ Good point; may I steal it? :o) or you're welcome to edit ... $\endgroup$ – Will Crawford Jan 8 '18 at 22:46
  • $\begingroup$ Feel free, mechs swinging chains is about as realistic as them fighting with chainsaws 5 metres long ;-) I have expanded the comment into an answer below. If you are going to use this in a book or story, Include me as that infantry guy going to take the mech out with an RPG shot to the knees. $\endgroup$ – Thucydides Jan 9 '18 at 5:37

Depends on how your mechs look. Do they have exposed hydraulic lines or control wires that can be cut? If so, then a cutting weapon like a sword may be very effective at disabling a mech instead of bashing it up. Very important if survival of the pilot or salvaging the mech is important. For example, lots of medieval melees were not to the death, but "to the surrender" of an opponent so you could ransom them back and keep, sell, or ransom back their gear. You can't do that if you killed the pilot and destroyed their stuff.

A weapon like a pick, or a war hammer (long shaft, small impact head backed by a spike) would be ideal for punching through armor or hitting critical actuating surfaces, sensors, and power systems. Movies like Pacific Rim show mechs with little in the way of actual mechanical parts, they are basically just men in armor. But real mechs have lots of areas with pistons that can be bent, hydraulics that can be cut or broken, and engine systems that won't react well to a hammer smashing a power cell or rupturing an oil reservior.

The piston punch is probably the most practical melee weapon as it would be easy to incorporate into a mech for those "just in case" melee encounters (so more like a bayonet to attach to a rifle than a dedicated polearm or sword to carry around) while firearms are the weapon of choice for warfare.


To know what kind of weapon, we need to know how agile are your meka

not agile mech

These type of mechs have a lot of limitations in their arm movement. Forget about swords, you won't be able to move quickly enough to slash properly. Same thing for a classical warhammer. Warhammer 40K Dreadnought

but using a kind of pneumatic spear (like this ) you would get a real goot penetration capacity and, if you ennemy is as agile as you he wont be able to dodge. with a bit of skill you can easly target the pilot, or weapon system and destroy your target in only one blow. Librarian

Nearly as agile as a human In this case, you have a lot more options for your gear because of the greater freedom of movement. Using a pneumatic weapon could still work but it wouldn't be the best choice because if you aren't stable on your feet, the recoil could knock you off balance. And you can't have that. If your opponent is able to dodge and land a deadly repost right away because you are not ready to dodge.

But, a hammer (see below) would be way more interesting as it can deliver a piercing blow to the joint of the enemy mech. This could disable your opponent or even kill the pilot if you land a shot by luck. Even if you are not able to pierce the enemy armor, the strike can cause a lot of vibration and maybe cause incapacitate the pilot or damage internal systems.


In any case, a sword doesn't seem to be a good option to me as long as the blade can't slice through armor. Stay with piercing weapon, it would be easier to make deadly in a mech battle.

  • $\begingroup$ Hey, welcome to Worldbuilding. I did some cleanup to your answer. You should be able to roll back my changes if you don't approve. $\endgroup$ – Green Jan 9 '18 at 1:39

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