I've decided I want a sword which in addition to being fully functional as a sword, can also fire energy ( or some other ammunition which can be produced when needed as opposed to being carried around) at enemies.

About the specs: -It is essentially a longsword with internal machinery, regular sword handle and all

-It should preferably be able to fire a continuous beam as well as individual bolts

-Preferably no openings in the sword that lead to the inner machinery

-Assume sufficiently advanced materials to account for the sword remaining durable, UNLESS you have a more realistic idea what it could be made of

-The actual nanotech of the sword should build on some existing scientific principle

-Energy supply may or may not be internal, although I'm leaning towards it being external

Given these criteria, how do I build this monstrosity of a weapon?

EDIT: Changed plasma cannon to energy rifle as it's a broader term for the kind for "ammo" I'm looking for, clarified a few things

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    $\begingroup$ See Are gunswords feasible? for why combining ranged weapons with melee weapons is generally considered a bad idea $\endgroup$
    – Anketam
    Commented Feb 7, 2017 at 1:38
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    $\begingroup$ The first thing to do is to imagine a reason why a plasma cannon would be an effective weapon... $\endgroup$
    – AlexP
    Commented Feb 7, 2017 at 2:47
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    $\begingroup$ Explain why a bayonet isn't acceptable. $\endgroup$
    – Spencer
    Commented Feb 7, 2017 at 4:09
  • $\begingroup$ Similar to D'argo's qualta blade in farscape? farscape.wikia.com/wiki/Qualta_Blade $\endgroup$ Commented Feb 7, 2017 at 6:51
  • $\begingroup$ Anketam, it won't have the same issue with ammo, structural weakness, and the handle is for sword use $\endgroup$ Commented Feb 7, 2017 at 7:25

4 Answers 4


Gonna go low-tech here:

Rather than using one blade, your sword could have two parallel blades that would act as the rails of a railgun. The hilt of the sword would house the firing mechanism, necessary electronics and the ammunition for a few shots. Power could come from a portable power pack (batteries, capacitors...) attached to the hilt with a power cord.

This seems the most feasible with current technology, albeit not necessarily very effective. And unfortunately can't fire beams of energy as you specified in your question.

For a stream of energy, the best I can propose would be basically a flamethrower with a sword attached. Another solution would be a laser.

The problem we face isn't really the form-factor of the weapon (sword rather than a gun) but the energy/ammunition requirements. To keep with the idea of the weapon, your best bet is to have something with batteries in the hilt.

  • $\begingroup$ I just googled plasma railgun and it's apparently a thing, I like this idea the most, and I could tweak the ammunition with need $\endgroup$ Commented Feb 7, 2017 at 15:15
  • $\begingroup$ Yes, if I recall correctly, the ammo used to create plasma balls for rail guns are thin sheets of conductive metal, so they get quickly ionized and heat up to become a plasma due to their high surface/volume ratio. $\endgroup$
    – Subbies
    Commented Feb 7, 2017 at 16:10
  • $\begingroup$ You could also ionize gases (and thus create a plasma). Keep the gases in a container with your batteries and feed the gas through the hilt like for the batteries. This, coupled with a fan (or maybe the electric current is enough, I'm not sure) could allow for a constant stream of plasma being fired. $\endgroup$
    – Subbies
    Commented Feb 7, 2017 at 16:22
  • $\begingroup$ That would make really bad sword. Either you have each blade half as thick and thus twice as fragile, or you would have it too heavy for normal use. $\endgroup$
    – Mołot
    Commented Feb 8, 2017 at 10:06
  • $\begingroup$ @Molot It will make a bad sword, but not for the reasons you specified. With all the added weight and internal mechanics, as well as the power cord, the sword will be more unwieldly than a regular sword. However blade thickness is a non issue since it will depend on the materials used as well as the blades profile. Look at historic swords from longswords to rapiers and the difference in their blade size and thickness. $\endgroup$
    – Subbies
    Commented Feb 8, 2017 at 10:32

Easiest solution is that the sword 'blade' itself is actually a plasma stream. That way, in order to make it fire a plasma bolt, it can simply fire a vortex out of the same opening the plasma comes from which should hold it together for a short while, while a beam simply involves ramping up the blade power (though without the vortex range would be shorter).

You may want to hand wave some powerful magnetic confinement, or else have a sheath that is kept inflated by the plasma pressure (this partially alleviates the heat problem, and makes your sword more solid).

Some things to consider if you're worried about realism: how is the sword powered, and more importantly, how does the wielder deal with the intense heat?

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    $\begingroup$ I'd say that's a lightsaber, I'm thinking something with a metallic blade $\endgroup$ Commented Feb 7, 2017 at 7:31

Ignoring all the usual stuff about "gun-blades", how aiming a sword like a gun is terrible, and how trying to use a sword with a handle designed for aiming guns would be equally terrible, you could conceivably do this with mechanisms built into the handle.

Have the quillions (the cross-guard end bits) generate powerful electromagnetic fields parallel to the blade. Perhaps augment them with a high-current coil wrapped around the base of the blade, and you should be able to fling magnetic/electrically charged ammunition along the blade. Think "Star Wars bowcaster" with a blade protruding from the front, but hilted like a sword. Similar to the rail-gun idea but without using a dual-bladed sword.

As an aside, cranking up the power could ionize the air around the the sword, creating a corona discharge, which would pretty effectively turn your sword into a sort of lightsaber (via plasma sheath) while also very quickly embrittling the blade. Might make for a good last-ditch attack.


how about this; your sword is a normal blade with an inner coil witch creates a magnetic field. The end of the hilt or the pommel is a small fusion reactor witch 1) powers the coil for the magnetic field. and 2) Produces plasma (witch envelops the blade and is held in place by the magnetic field). a violent swing could 'trow' plasma at the opponents (I myself doubt the scientific accuracy of this). I will give some thought to your individual bolts since I have no answer to that yet.

the blade would be made of ceramics not iron since it is more heat resistant.

  • $\begingroup$ Doesn't seem like a ceramic blade would be sufficiently hard to actually use in battle $\endgroup$ Commented Feb 7, 2017 at 15:22
  • $\begingroup$ @ArborianSerpent Maybe use a tungsten based alloy instead? You could also mess with the magnetic field to launch the plasma. $\endgroup$ Commented Feb 7, 2017 at 16:30

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