Design for an Extendable Melee Weapon?


I've been working on a RolePlay setting, for me and friends. The setting mostly uses energy weapons, and at the higher levels, anti-energy shields (Beam deflecting shields, or laser reflective materials). This comes with a trade off, leaving energy shielded targets vulnerable to material weapons, such as bullets and melee weapons.

Which are far, far less common. Since one cannot dodge a laser, but can move away from a projectile impact.

The setting has power armor, and is fairly high-tech. Advanced enough for 'heat sabers' and 'vibrating sabers' which make mince-meat out... Most things, and 'Thunderhammers' jack hammers that explain blunt force trauma, in detail, to the those ignorant of it.

Since the average battle involves heavy firepower, ammunition can easily run out, having a melee weapon is a fairly good back up. Ignoring major problems, such as closing the distance, we reach the issue I'm having.


How, exactly, do you compact a melee weapon IE; a halberd. Into a form that does not expose your silhouette to targeting programs and the like. Then somehow, extend back to fighting form when needed.


How to design weapons that are compact, capable of extending back into normal form?

(Being compact and capable of extension, are not required traits. If the solution still saves of on volume while being practical.)

  • $\begingroup$ how to you feel about using nanobots that can rearrange themselves into various forms? $\endgroup$
    – Nosajimiki
    Oct 21, 2019 at 22:02
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    $\begingroup$ Depends on how practical they are. How do you send, and receive signals? How heavy and how much structural integrity do they have? I do like the idea though. $\endgroup$
    – Rosegold
    Oct 21, 2019 at 22:08
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    $\begingroup$ Why is it important that the melee weapon not provide a noticeably different silhouette? In your example of a halberd one could simply have the blade embedded as part of the chest piece of the power armor, or the back and then have a folding/extendible handle. Slam a pneumatic trigger on the chest piece, out pops the melee weapon, quickly unfold and twist the handle and bam, near instant melee weapon. I don't understand why it needs to be compact though? If we're talking high tech, then a short handled heat saber attached to or even embedded in some part of the armor would work, no? $\endgroup$ Oct 21, 2019 at 22:26
  • $\begingroup$ Focus fire. If they see a heavy plated power armor, it's just that. If it's a heavy plated armor, with a sword, then it needs to die. Generally speaking, the longer the blade, the more killy a weapon is. $\endgroup$
    – Rosegold
    Oct 21, 2019 at 22:32
  • $\begingroup$ What is wrong with a basic baton? Seems like that is exactly what you want or am I missing something? $\endgroup$
    – lidar
    Oct 22, 2019 at 0:16

4 Answers 4


Mechanized melee weapons have been experimented with, and they are the exception, not the norm, for a few very good reasons.

pistol-swordgun-axelantern shield

Basically, the more complicated an item is, the less durable it is.

Let's say that a blade made of some fictitious metal we'll call Aresium can be expected to withstand a 1 million joule impact per cubic centimeter of material. Let's say that, in the shape of a medieval longsword, is enough to get through the gaps in Power Armor. Here comes the problem: if you want it in the form of a retractable item, then you run into the chain-link issue: a mechanism is only as strong as its weakest part.


If the blade folds on an Aresium mechanism whose smallest part is only half a cubic centimeter, then the weapon will break under the expected combat stress. To get the weapon to a minimum impact-ready level of sturdiness you need to make the smallest part of the mechanism twice as thick, which means making every other piece thicker to compensate, which adds a lot of weight and bulk, which is exactly the kind of thing you're trying to avoid in the first place by making it retractable.

The other problem is that the more complicated something is, the harder it is for a person to intuitively use. Have you noticed that a game of chess goes way slower than checkers? Now I'm not saying everything has to be simplified to oblivion, but when you're under stress, the less things you need to think about the better. People who actually know what combat is like don't want complicated gimmicky weapons because it'll slow them down. And in battle, half a second is all you have to save your life.

Solution: Don't bother with fancy gimmicks. Just make your melee weapon incredibly sturdy and stout, if you want it to be carried around as a sidearm.

And as you've said, melee weapons are rare in this world because they're only used if you happen to run out of ammo while the fight is still on, so you shouldn't be looking to things like halberds for inspiration, but rather to swords and knives.

Of course, if strength-enhancing power armor is part of the equation, then it's worth considering that a melee weapon is kind of redundant. Just punch the guy if it gets to that point, and it'll probably be lethal. A melee weapon would be marginally better in the sense that the wielder is more likely to win if the opponent is also out of ammo, and less likely to hurt his hand, but that scenario would be rare enough that most soldiers don't bother to consider it.

Dwarven Dagger

By Ysmir, if it's simple and strong, I can forge it.

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    $\begingroup$ Not sure I buy the simplicity argument - a gun is far more complicated than a mace, but there are enough advantages to make the gun preferable in most circumstances. If a little extra complexity means you don't have a target drawn on your back, the collapsible weapon may be well worth it. $\endgroup$ Oct 22, 2019 at 16:47
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    $\begingroup$ A gun isn't meant to be used to bash someone over the head, facing multiple consecutive impacts in unpredictable locations, angles and force. The mechanisms of a gun are custom-fit to contain gas explosions in a specific chamber, then feed a new bullet into the same chamber. Ask a gun expert to what extent it's safe to slam the body of a rifle into the side of a car and that's the kind of impacts we're talking about for melee combat with power armor. $\endgroup$ Oct 22, 2019 at 16:51
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    $\begingroup$ No clue how you read my comment as suggesting that you should use a gun as a mace. My point is that "the more complicated something is, the harder it is for a person to intuitively use" can be outweighed by increased utility of the more complicated object. $\endgroup$ Oct 22, 2019 at 17:17
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    $\begingroup$ Sure, that can easily apply to long-ranged weapons, but not so much when you're staring down a big, scary angry man just out of arm's reach who wants to kill you. Something as simple as needing to click a switch to deploy the weapon, could be one step too many for someone under duress. Plenty of men historically have been stabbed to death for want of being able to get their sidearms out of their sheaths in time, and they didn't have hypothetical extra bits and bobs to worry about. $\endgroup$ Oct 22, 2019 at 17:25
  • $\begingroup$ Regarding this bit: "To get the weapon to a minimum impact-ready level of sturdiness you need to make the smallest part of the mechanism twice as thick" - that's very true in real life, but - given the tech involved in this question, how about achieving the sturdiness not through thickness, but through some technological handwavium based on pumping energy into the weapon in it's expanded form (reinforcing force field, nanobots repairing any fractures and cracks between blows, having an expendable striking part or one not made of material but something like a direct plasma jet etc. etc.) $\endgroup$
    – G0BLiN
    Oct 23, 2019 at 12:40

Considering you are working with really hi-tech power armor, we can assume that these EM shielded suits will also be taking advantage of materials at least as good as we have at our disposal today. A simple layer of graphene thinner than a sheet of paper will make this armor impenetrable by any normal melee weapon; so, it stands to reason that your melee weapons would not kill any better by impact or cutting than a plasma cannon would by heat. Instead they will need to bypass this armor in a way those ranged weapons can not.

A second consideration is that melee weapons are very rarely needed in a modern battle field. Since WWII, many militaries have trained their troops to use the battlefield tools that they already need as melee weapons so they are not carrying any extra weight.

Bring in the Nanobots:

In this situation, the nanobots will be a "swarm" of tiny robots that can crawl over each other at the microscopic scale, then interlock to become a solid form. (Think T-1000 from Terminator 2). This nanobot swarm can take on any shape for transportation such as forming a bracer around your wrist, or a brick you keep in a cargo pocket, etc. Being able to take on any shape, it is the ultimate field survival tool, it can become a shovel, a pick axe, a machete, a screwdriver, a spool of razor wire, a wrench, etc. Even if you never get into melee, it is still something every soldier would need, making it a logical investment.

While it may be assumed that this swarm of robots with all their little legs and machine bits would be brittle, materials such as graphene, carbon nanofibers, and synthetic goethite are so strong that even used sparingly, an interlocked nanoswarm could easily become strong as steel and as hard as diamond... which should be strong enough for all of your field tool needs.

When you get into range of an enemy, this tool can "come to life" and attack the opponent like a living tentacle, it will seek out the most vulnerable part of the armor (such as a breathing vent), and force its way in shredding through air filters and crawling in through the victim's mouth and nose where it has free reign to rip apart the squishy internal human bits with ease.

If you specifically want it to look and feel like a melee weapon, this is doable to. It could form into a long mace or war hammer, and on impact the head detaches and begins spreading out over its victim looking for soft spots to get into.


Some harebrained ideas for hi tech melee weapons...

  • Force field sword. Shape the weapon in whatever way you "normally" shape your fields, only this time the goal is something sharp and/or pointy. Perhaps a plane of force? Hard to explain unless your suits already have force fields, at which point this is just shaping the field around your hand (for example) to extend it into something dangerous.

  • Monomolecular whip (with a little weight on the end to give it some control, or gravity manipulation, or more force field mojo to shape it as you like). Easily extended or retracted, ridiculously sharp, can be dangerous to the wielder.

  • Someone else mentioned "inflatable". It need not be inflated with a gas. How about a fluid? How about a non-Newtonian fluid? One that becomes solid with sufficient impact? Something like corn starch in water will harden when exposed to low frequency, forming standing waves. Throw in "a sufficiently advanced technology", and you don't even need a flexible tube to hold the fluid, you can just vibrate it into the shape you want, and slurp it back up when you're done.

    • Bonus points if the end result is a fractal, because that sounds like something a series of vibrations would induce in the final shape. Flamberge + Mandlebrot = Mandleberge!
    • Bonus points if your armor is already using some of said fluid to make it's joints flexible but still harden on impact... at which point this is merely weaponizing your refill tube.
  • I had this crazy idea for a magic world setting you could apply using Sufficiently Advanced Technology: The ability to change an object's mass based on the "frame of reference". As far as the grip is concerned, an object might weigh 1/N of its actual mass, while from the business end, it could weigh xN times its actual mass... so make N = 4... or 1000. Combine that with someone's idea of a memory metal belt/sword, and you have something that can apply a ridiculous amount of kinetic energy in a very small space, and is easy to carry. Or an Asp-like collapsing baton that hits like it weighs several tons (being swung by someone as though it had zero mass). This sort of thing would have to be parried by something similarly affected... or just huge.

  • Non-traditional melee damage. Weapons that look like swords or spears or whatever, and are used that way...

    • ...but are actually hacking tools that need to be close enough to work on enemy armor/gear/whatever.
    • ...but are actually capable of doing something Really Unpleasant at the business end that doesn't involve impact. "de-bonds oxygen atoms", "cloud of unstable sub-dimensional pinholes", heat, vibrations, gravity, EMP. Give any of these effect the range of a few millimeters, and it makes for a convincing melee weapon. Not sure how to explain parrying. Hmmm
  • $\begingroup$ Good ideas as far HOW to inflict enough damage to penetrate power armor, but you should also address the collapsibility function, and how these ideas correlate with it. $\endgroup$
    – Nosajimiki
    Oct 22, 2019 at 18:41
  • $\begingroup$ As soon as you remove "physical impact" as the cause of damage, you dump a bunch of the structural requirements for said weapons. You can suddenly get away with some pretty flimsy stuff because the physical durability of the weapon isn't nearly as important. $\endgroup$ Oct 23, 2019 at 12:42

So I can think of a few ways to get weaponry that will extend.

  1. As Nosajimiki mentioned in comments, nanotech should be able to do this, though I would assume that it would only hold it's form when you're providing it power.

  2. Memory metal wouldn't expand per se, but could move from say a belt to a sword maybe? Again, you'd have to provide power of some form to make the change.

  3. How about an inflatable weapon? Especially if you inflate via a foam that creates a (semi) solid interior to the weapon. Disadvantages to that would be it probably would take a couple of seconds to expand and solidify, and once it's expanded, it probably won't be able to be compressed again.

  4. Finally, how about your standard expandable baton as lidar mentioned? Something like the denn'bok the Rangers used in Babylon 5 if you want a more high tech version - https://babylon5.fandom.com/wiki/Denn%27bok.

  • $\begingroup$ There are extendable staffs as well as batons: inspireuplift.com/products/expandable-magic-metal-staff With good enough materials, you can make a hammer with expandable handle. And you can have segments twist to lock, so it cannot collapse during a thrust. $\endgroup$
    – Bald Bear
    Oct 22, 2019 at 16:41

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