I was wondering what benefits are granted when a sword is either on fire or emitting flames. I once read that such a weapon would be completely useless, as it would cauterize any wounds it inflicts, but there has to be some benefit.

What are the advantages of a flame sword in melee combat?

  • $\begingroup$ Very related! Though answers were intended for heavily armored targets, because mechs. worldbuilding.stackexchange.com/q/8609/2138 $\endgroup$ Dec 22, 2015 at 22:09
  • $\begingroup$ Well its going to have a very hot hilt in a few minutes.... $\endgroup$
    – Oldcat
    Dec 22, 2015 at 23:44
  • 1
    $\begingroup$ Ever heard of a movie called star wars? $\endgroup$
    – DJMcMayhem
    Dec 22, 2015 at 23:49
  • 2
    $\begingroup$ "...such a weapon would be completely useless, as it would cauterize any wounds it inflicts." Cauterizing is far from pain-free! $\endgroup$
    – Xoque55
    Dec 23, 2015 at 3:56
  • 1
    $\begingroup$ Short version: It would look amazing. $\endgroup$
    – Kaz Wolfe
    Dec 23, 2015 at 11:58

9 Answers 9


While a flaming sword would certainly have a psychological effect on people, unless it was emitting a white hot flame (@ 1600 degrees C), it would not be as effective as a metal sword.

Consider that the mechanism of injury would have to be the transfer of heat to the target. A red hot sword (at a mere 800 degrees C) would have to be held to the target for a period of time, more like a branding iron than a sword, in order to transfer enough heat to cause injury. If the target is protected by armour, then the mass of metal and the protective undergarments need to be heated enough for the heat to transfer through them first (and the masses of metal, leather and quilting would both spread the heat energy and provide insulation to the target as well).

A red hot sword would also be far too cool to melt metal armour, and would have difficulty setting fabrics on fire with a mere swipe or quick thrust. Since the padding was usually sheep's wool, flammability isn't going to be an issue. Even striking a shield isn't going to cause a catastrophic ignition event, try setting a sheet of plywood on fire with a quick sweep of a blowtorch and you will get the idea. Indeed, you can quickly swipe a blowtorch across your own naked skin and feel the heat or suffer a first degree burn, rather than cutting through your arm...

Greater heat allows you to overcome these issues to a certain extent, providing much more energy to transfer to the target, but in general, a flame sword would have to be used differently from a metal one. The best attack would have to be a thrust with the flaming blade to the face, since even the best helmets need to have openings to allow for sight and breathing. A successful thrust could blind the enemy, or they might breath in the flame, both rather horrifying ways to die.

Given the relative lack of effect of a flaming sword, the terrible deaths that it does provide and the pretty instant identification of the user once drawn, I suspect that a flame sword would simply invite the wielder to die under a hail of crossbow bolts, followed by attacks by polearms so the men at arms will be at a safe distance but still able to strike killing blows if the archers hadn't gotten him first.

  • 11
    $\begingroup$ Erm, I think OP meant a metal blade that is emitting flames or on fire and not a flame blade per se. $\endgroup$
    – Bounce
    Dec 22, 2015 at 9:44
  • $\begingroup$ You don't need to melt an armour - if it's hot, you're going to cook your enemy. Being burned will result in such pain that he won't be able to fight, and hot sword will be too hot to hold it - and since transfers heat quickly, this will result in ugly wounds. Also remember - people aren't always fighting when they suspect it, and psychological effect can be great - if you had the flame sword in the prehistoric times, you would surely look like God's messenger. But I'm surprised that no one has asked the question: how would you store and transport it? $\endgroup$ Dec 22, 2015 at 11:12
  • 2
    $\begingroup$ I used a blow torch on some scrap plywood outside, and it reached my car. No more car! -1 for destroying my car with burning plywood after seeing your answer! Jk $\endgroup$ Dec 22, 2015 at 21:10

For a few years I learned how to fight with medieval weapons. Some people I met then had their swords put on fire (in this case, with oil on a wick, so it was for a short time)

It was beautiful and impressive ! But not very effective.

Of course they did not use it to fight an army for glory. It was a choregraphic fight and the "enemy" should not be hurt or frightened. The public was impressed, the noise of the flames and the light were spectacular, but the fight itself has to be quite slow and simple.

The flames are as dangerous for the owner of the sword than they are for the opponent. If you want to protect yourself in a swordfight, you have to keep your sword very close to you. Keep your hair tied and protected, and make sure your clothes won't ignite. And you will have to wear good gloves, as your wrists will stay very close from the heat during the whole fight.

As long as you move quickly there is no problem, neither for you or your opponent (as it has been said, the heat don't hurt you if you don't let it on your body for a moment), but in a real swordfight your swords will meet, and stop, and then move again. Your opponent's moves will bring your own sword to protect you, thus put it very close of your head, your eyes, and you don't want flames near your eyes.

Perhaps, if you manage to hurt your opponent with your flaming sword, it will hurt him more than a regular sword. Burns are very painful, but so are "regular" sword injuries. If you manage to hurt your opponent, a flame sword will be a little more cruel, (burns are painful and take a long time to heal) but it won't help you win the fight, except if your opponent is terrified by your mighty flaming sword and run away as soon as he sees it.

  • 2
    $\begingroup$ One could say, that during a hard block, the flammable substance could be spreaded over your enemy due to inertia, which would give you some advantage... ;) $\endgroup$
    – Bounce
    Dec 22, 2015 at 9:48
  • $\begingroup$ I am not sure that the flammable substance is the best way to have a flaming sword (for a battle). From my experience, the liquide was in the wick to avoid spreading, and if it spreads, it could be on you, too. But with a little more practice, it could make a flamethrower sword, yeah ! $\endgroup$
    – Tyrabel
    Dec 22, 2015 at 10:03
  • $\begingroup$ Ah, I didn't know the term "wick". Looked it up :). I meant some kind of burning paste, that sticks to the blade and only spreads if you really have some moment of inertia, so you can throw little fireballs on your enemy :D $\endgroup$
    – Bounce
    Dec 22, 2015 at 10:10
  • 1
    $\begingroup$ I'm not a native english speaker, I found "wick" with google translate, it might not be the best word. But still, i like the flame thrower sword :) $\endgroup$
    – Tyrabel
    Dec 22, 2015 at 10:15

God thought it was a good idea.

So he drove out the man; and he placed at the east of the garden of Eden Cherubims, and a flaming sword which turned every way, to keep the way of the tree of life. Gen 3:24, KJV

You think you are wiser than God? I think the intimidation value of the fact that you are so butch that you do not just use a sword, but a flaming sword has to be worth something.

Humans and animals justifiably have a deeply held fear of fire. It burns us, and often escapes our puny attempts to control it. A weapon that your enemy fears works even when you don't have to wield it in combat.

Whether the flaming sword gambit is a good idea for a human wielder is perhaps a different question.

One clearly negative aspect of a flaming sword is that you are compromising the strength of the metal. At temperatures above 900 C, steel loses about 90% of its strength. This is very bad for battlefield use.

Human soldiers are not as butch and do not have the superior grade weapon material qualities of angels wielding divine swords. Lose the flaming sword.

Lastly, if you are primarily interested in a torch with limited utility as a weapon, well perhaps you are using the right tool after all.

In case English is not your first language. Describing an angel as butch is a whimsical means of describing angels as extremely manly, possibly an irreverent usage. Butch does not necessarily reflect common modern usage as manly lesbians. My only intent was making this light-hearted, no offense was or is intended. I simply intended a light-hearted description to counter the idea that I was engaging in a serious theological discussion. Clearly worldbuilding is not the place for that discussion.

  • 4
    $\begingroup$ What's the relevance of the religious commentary in this answer? $\endgroup$
    – Frostfyre
    Dec 22, 2015 at 5:19
  • 13
    $\begingroup$ Why not, its worldbuilding. whether mythological or real, a flaming sword is an ancient concept. Perhaps many are unfamiliar with this aspect. $\endgroup$ Dec 22, 2015 at 5:22
  • $\begingroup$ At least it is a prove that man is wiser than that god, or at least the author of the religious text. $\endgroup$
    – his
    Dec 22, 2015 at 7:17
  • 7
    $\begingroup$ Actually, in the actual case of Genesis, it would be wise to deploy an angel with a flaming sword, in fact the very first weapon -- you are more intimidating to an unarmed pair of humans in which you do not want to actually engage in battle. It also is an exceedingly rare circumstance in which it would be advantageous to use a flaming sword. Part of the real reason for bringing this up at all, that and fact it is a very ancient concept. $\endgroup$ Dec 22, 2015 at 11:44
  • $\begingroup$ "I just put the fission in there to add backstory to the layout of resources, you weren't supposed to make a bomb out of it!" -- God, probably. Necessity is the mother of invention, and we've necessitated the heck out of weapons development over the years. Presumably God doesn't need to be too inventive about this sort of thing -- any envoys or messengers can just be set to invulnerable or re-created as necessary. $\endgroup$
    – Zwuwdz
    Jan 26, 2023 at 16:07

A flaming sword can't be grabbed

Though it's not often shown in movies and fantasy games, grabbing the edge of a sword (your own or your enemy's) was not uncommon.

Sometimes a knight would flip his sword around, grab it by the blade and swing it like a warhammer (the mordhau maneuver).

(source: warosu.org)

Sharp blades would deflect off of full plate armor, but the concussive force of a blunt weapon could transmit through the steel and hurt the knight inside, or perhaps dent the armor and immobilize him.

A sword with a burning edge probably could not be grasped (unless your warrior also has asbestos gloves). This would make maneuvers like the mordhau impossible, restricting the sword's utility.

However, a flaming sword would also be difficult for the enemy to grab, changing the tactics a foe must employ.

  • $\begingroup$ Exactly what I was thinking. Although "asbestos gloves" seem like suitable equipment for someone wielding a flaming sword! $\endgroup$ Dec 23, 2015 at 7:24
  • $\begingroup$ Or the flames are enchanted to not hurt its wielder, in which case half-sword away! $\endgroup$
    – 0xFFF1
    Oct 16, 2020 at 1:59
  1. Psychological and morale effects. It's going to get people's attention and intimidate and surprise them and make them wonder what's going on, and probably inspire some fear and confusion. Also, metal doesn't usually burn, and flaming oil also doesn't burn well when put on metal and swung about. So if you have a seriously-burning sword, it's going to make people wonder what's going on, at the very least. It's not going to look like something most people will want to risk getting hit with. Not to mention that you may make people wonder if you have some sort of supernatural assistance. Your foes may cringe, flee, falter, freak out, or at least be thrown off their usual behavior. People on your own side may also quite like having you on their side - you may inspire them, or at least they may like that you are attracting so much enemy attention.

  2. Hot metal hurts to touch, so people you cut may suffer additional pain.

  3. You can now easily set flammable things on fire. If your sword produces plenty of fire even while swinging around, it probably will light up cloth and straw quickly, which might be useful. If an enemy is for instance in metal armor under a nice cloth surcoat, for instance. Or perhaps you are pillaging, or want to create a fire obstacle, and there's dry grass or hay around.

  4. You won't have to worry about darkness.

  5. Animals in particular may not want to attack you. You might be able to spook someone's warhorse.

  6. However you are managing a flaming sword, may also be an advantage. For example, if it's covered in Greek Fire or some sort of pitch/tar, that may also add pain and flaming sticky goo to anyone you hit. Or if it's flaming because it's magic, the magic may also make it more effective in other ways. Or if it's flaming because some god of fire has blessed it, his blessing may also have other effects...

  • $\begingroup$ Darkness is still a problem. If your eyes are dark-adapted, one swing of the sword and you lose that. You won't see enemies until you're close. Of course, this is not reciprocal, since enemies will see you. Actually, darkness looks like more of a problem with a flaming sword than an ordinary one. $\endgroup$ Oct 23, 2018 at 21:18
  • $\begingroup$ @DavidThornley I'm thinking that the sword could provide constant illumination like a torch does, in which case you wouldn't get dark-adapted. This does have some of the problem you point out, in that you're holding the light source so smart foes might stay in the dark and use ranged weapons on you. However it's better than typical approaches to darkness such as carrying a torch or lantern which takes up one of your hands during combat. $\endgroup$
    – Dronz
    Oct 23, 2018 at 21:57

Really, the power of a flaming sword beyond the merely psychological would be entirely dependent on the properties of the sword in question. Since the others have basically answered your question with the 'no' answer, allow me to be contrary.

First of all, since the sword doesn't burn itself into a wreck while being ablaze, we can safely assume it is a magical blade, or at least emits magical fire. If so, perhaps it protects its user from its own flame. If it does, this expands its possibilities by a huge amount.

  1. We can increase the blast radius of the flame, turning the wielder into a literal cyclone of fire. This would provide incredible area control, as you could threaten a large group of people just with this sword.
  2. Alternatively, the blade could be ridiculously hot, like arc-welder hot, enabling its wielder to cut through men and walls like a literal hot knife through butter.

So yeah, maybe a bit too fantastical for your liking, but probably cooler than a normal sword ablaze in burning pitch.


Here's a magic-free (if rather impractical) solution.

Perhaps you could have a sword with a fuel delivery system built in. You'd need a pilot light always burning -- that could be fed by a wick -- then a trigger to release a dose of fuel down a hollow blade. That would mean that you could block without the flames coming too near you, and still deliver serious burning damage. Despite the ancient use of Greek fire (wikipedia) it wouldn't be a good fuel in this case as it needed significant preheating.

Even better would be pyrophoric (self-igniting) liquids (wikipedia). Again you'd need manual control of delivery.

When it comes to how it would be used, either way you'd have a short-range flamethrower combined with a sword, not so very different from a pistol-sword (wikipedia), but with the psychological effects of fire weapons. The flames could be used mainly before joining in close-combat -- perhaps they would spread far enough to be useful against an enemy with pole-arms.

Against an armoured foe, the flames could be quite effective, similar to how flame-throwers were used against bunkers (wp again) to great effect. Essentially because the flame can enter though any opening in the armour and then spread it can cause serious harm without the need to penetrate armour. Flames passing in through existing openings/joints, even if only painful and not lethal, would certainly affect an opponent's ability to fight (especially considering eye-slits). If a sword could open up a new hole in the armour then inject flames, it would be all the more effective.

The fear factor involved with fire might mean it would be used as a torture weapon as well.

A reservoir would have to be reasonably well protected, as would the fuel line, otherwise damage to the fuel line would be a serious vulnerability, especially with pyrophoric liquids.

  • $\begingroup$ This does not answer the question. OP is asking for advantages of flame sword, and you provide an example implementation of the given sword - which is off topic. $\endgroup$ Dec 22, 2015 at 11:54
  • $\begingroup$ @MatthewRock, perhaps it's buried in the third paragraph, but I wanted to describe it before explaining what it would do. I'll expand the use description, but moving it to the beginning would take too much rewriting. $\endgroup$
    – Chris H
    Dec 22, 2015 at 11:58

The overall advantages of each

Normal Sword: simple
Flame Sword: complicated
Flame-thrower: longest range and largest area of effect

Flaming swords, as we currently think of them, involve many complications without any "real" advantage over other weapons which use the same concepts. This makes the complications its strength, because hopefully people won't understand what they are facing and they will be afraid.

  • Fuel and overall design
  • Blade integrity (hotter usually means softer)
  • Danger to self
  • Relatively more training compared to both normal swords and flame-throwers.
  • Doesn't seem to solve a real combat problem, due to not being any more effective at causing harm compared with a normal sword?

But let's say we could have an effective flaming sword, what would it have to be like?

  • Probably operates basically like a lightsaber from Star Wars - complete with advantages of burning through most things near-instantly and easily while requiring little or no fuel.

Of course.. the real problem with that is the tech level involved. If a lightsaber just randomly showed up on the battlefield today, the user would still just get shot. If it randomly showed up in a medieval battle, I suppose the person would still get shot with arrows. Randomly showing up at a medieval duel? I guess you've found the right moment to pull it out, so long as you are more likely to be portrayed as the son of a deity rather than an evil demon.



What if the flames engulfing the sword dinamically flow on the sides of the sword giving aaddictional thrust like a spyke thruster engine (more correctly a linear spike engine like the one made as prototipe for the x project spaceplane... Sorry i forgot the name of the Xproject)

In coordination with the wielder moves it could ad more power to the hit, a more acurate edge alignment (since the sword are automously directing themselves) and if the thrust controll of the wearer are fine enough are possible to perform some "impossible" moves and angles of attack

The issue is how you could have controll over the sword and after that the handling of that sword need a completely new skill set, almost a new martial art

  • $\begingroup$ Just a suggestion, a screenshot and/or link to the sword in question would be a great addition to this post so that the OP could see an example. You can also add a link to any relevant sites. $\endgroup$
    – John Locke
    Oct 23, 2018 at 0:01

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .