# Weapon developed in modern melee only world

Let's say a global law has been passed in the year 2000 that disallows any projectile, explosive or otherwise long distance weapon or put differently, only allows variations of melee weapons. Thrown weapons (like throwing stars) are also banned. The reason for this was that weapons became more and more weapons of mass destruction and after the success banning chemical warfare it was decided to go down that route a lot farther. So what kind of weapons would be developed in such a world? Do thus feel free to assume that 1) everybody obeys these laws 2) even more money than in the last 14 years was spend on weapon development, so weapons can be a bit fantasy-like/unreal from our perspective. and 3) armor might have gotten better.

I am looking for something that could develop within 50 years of the ban (so out to 2050).

To be precise, I am actually trying to think of the back story for the development of a very specific type of weapon and am trying to find out whether this would actually give rise to such weapons. I might self answer later with that line of thought, but I would absolutely love seeing what you guys think.

And just to be clear, anything that doesn't put the user physically in the battle, physically being connected to the entire weapon does not count. No javelins, laser beams, bullets, etc.

• How do you get criminals to obey these laws? Especially if the cops and army do? – Oldcat Dec 5 '14 at 19:42
• I'm reminded of Dune. High velocity impact weapons become infeasible due to personal shield generators. Low velocity (stabbing) weapons become preferred. Knifes rule for personal combat, with fighting styles optimized to pierce the opponents shield at just the right speed. – Tonny Dec 5 '14 at 20:15
• Yeah, because criminals follow laws (nevermind otherwise law-abiding people who would object to a global law)... The law you need changed is a law of physics. Don't balk, it's a simpler change than entirely rewriting the human psyche. – Smithers Dec 5 '14 at 22:00
• Read this book en.wikipedia.org/wiki/All_You_Need_Is_Kill , it will help you to visualize the conditions in which projectile weapons become useless. Some are, many agile enemies or swarm like tactics. Guns are good in people vs people comba, fighting one other person with 300 rounds is fine because one well placed shot can kill him. He also makes a good target, people are quite big. However imagine having 300 rounds and being attacked by 400 rats or other small rodents, I doubt you will be able to kill even 50 before you run out of bullets or die. Hitting something that small is hard. – unom Dec 5 '14 at 22:36
• in Tenebreuse saga (McCaffrey), there was a global opposition to range weapon. This was due to a war where psy powers were used at distance. Any one using range weapon would face the wrath of every other people. Nobles would throw everything they got, even forgotting feud between famillies, to kill the miscreants. – PATRY Guillaume Dec 9 '14 at 18:40

I don't think that melee weapons would significantly change in 14 years of development, other than some re-purposing of tools designed for other uses. Lightsabers and other similar future weapons are, as of right now, purely in the realm of sci-fi, and aren't well supported by modern science. I do, however, see some changes to existing melee weapons, development of new weapons, and development of related battlefield technologies likely:

### Changes to existing weapons

Changes to existing melee weapons would fall mainly in terms of manufacturing process and materials. I imagine that something like a sword or a spear would consist of lightweight, durable modern materials like titanium and high strength nickel alloys, similar to what are seen in aerospace applications. Shock absorbant technologies have also progressed significantly, so work would probably be done in hilt/handle design to make weapons easier to maneuver in combat. It would also probably be possible to develop powered gyroscopic systems for controlling the rotational inertia of a weapon, making it easier to swing harder and recover from swings faster.

### Development of new weapons

Existing technologies like captive bolt guns might also be adapted as a way to increase the lethality of weapon users. Weapons could also be adopted from tools like chainsaws and jackhammers, though the weight of such systems may be prohibitive. Complex weapons with lots of moving parts would also be more susceptible to being damaged or broken in combat.

### Other technologies

For military applications, melee combat would put far more pressure on armoring and strengthening combatants, which would lead to probably the biggest technological shift in militarily combat: powered armor. This is a technology that's already being developed, and I imagine that a few hundred billion dollars could rapidly take it from something that is being developed to increase mobility in disabled people to a powerful battlefield weapon quite quickly. Without the threat of being destroyed by far cheaper weapons systems like RPGs, powered armor could make a fighter virtually invulnerable to the kind of damage that other soldiers could do with hand held melee weapons, no matter how advanced those weapons are.

Tactically, armored vehicles would have an even bigger advantage than they do now. A tank equipped with cutting blades could mow through infantry with impunity, since the elimination of explosives and projectiles would remove almost everything that infantry could do in response. I imagine the only thing that could stand effectively against a melee tank would be soldiers in powered armor, which would probably have better agility than the tank, and could effectively wield heavy power tools for puncturing their armor.

• I wonder if a shaped change that you manually attach to a vehicle would be allowed. That would probably change the infantry vs. armor dynamic, especially if you had some sort of retracable arm for placing it. – KSmarts Dec 5 '14 at 19:36
• Additionally, imagine the kind of "powered" melee weapons we could have. Say a lance that propels forward at high speed, or a sword designed to extend spikes outwards after impaling an enemy. You could get very creative with killing, maiming, and even "peaceful" applications by using advanced technology with melee-type weapons. – Thebluefish Dec 5 '14 at 19:40
• A tank without a projectile weapon is pretty useless. The Infantry could just stand up and move aside. – Oldcat Dec 5 '14 at 19:41
• They'd also be great for breaking up infantry formations clumped together to defend against things like motorcycle cavalry. – ckersch Dec 5 '14 at 19:52
• I suspect that weapons would probably use composites in addition to metal alloys. Just look at the javelins used in the modern olympics, or composite bats in (non-major-leauge) baseball. – 2012rcampion Dec 5 '14 at 21:13

With that kind of restriction, people are sure to turn to Loophole Abuse (warning: TV Tropes link). The requirement that the user be holding or connected to the weapon while using it doesn't strictly prevent the use of all ranged weapons. Anything that is thrown, launched, or shot, but still held or connected by a rope, chain, or cable sounds like it would still be allowed. This would include things like meteor hammers, gladiator-style weighted nets, or, as GrandmasterB observes, a taser.

I picture people creating hand-cannons that shoot spears, cannonballs, or nets with light cables attached. There would be a mechanism for quickly retracting the cable, or, in case an enemy got ahold of it, detaching the cable.

This may not be particularly effective in battle, but they could be used a few times a the beginning of a fight before closing range--just like Roman javelins, except they're technically still handheld.

• "I've got a bow and arrow, but it's a melee weapon because all of the arrows are connected to me with pieces of string." – ckersch Dec 6 '14 at 18:28
• How about a en.wikipedia.org/wiki/Wire-guided_missile? – March Ho Dec 25 '14 at 14:16

I could see the extensive use of electrical stun weapons. From small, concealable hand-held stunners to long pike-like devices with a lot of reach. They are cheap and easy to make, effective, and can 'scale up' to be used against armored opponents.

Traditional 'Taser' guns might also be used, based on your boundaries, because the barbs they shoot are technically connected by wires to the gun.

• Not technically connected, they are connected. – Oldcat Dec 5 '14 at 18:24

Huge mindset shift is needed in order to make the ban happen:

I am just going to list several "honorable mentions" of people or states or organisation drastically changing their approach:

• The Mafia everywhere, generally organised crime members will suddenly care about law... because laws should be followed.
• Democratic Peoples Republic of Korea (a.k.a. North Korea) will hand out all their weapons in fear of international sanctions. And we all know, that sanctions worked well against DPKR
• All protectors of second amendment in USA will understand it the same way as I do, and it is: The right to have weapon means actually sword and not firearm
• All history freaks, doomsday preparation freaks and everyone will hand out their weapons

And yet...

After doing so, they will return home and Taliban will continue plan of attacking the World Trade Center, and George W. Bush will invade Afghanistan (using swords only) ... and so on.

To me, ultimately:

If everyone will be willing to follow the "no firearms" law, it means world peace

After handing out all their weapons, the only plausible way to continue is, that North and South Korea leaders will shake hands and say "we both are Koreans, so why fighting?" Taliban will apologise to US, African leaders (Gaddaffi was still alive to name one) will throw in democratic elections ... And world will become happy place.

So, the initial setup cannot plausibly lead to any meele only weapon

• I purposely avoided attacking the ridiculous premise, but I'll give you a +1 for doing so, even though you didn't answer the question asked. – IchabodE Dec 5 '14 at 21:23
• Limitations on warfare were maybe working to some extent. What I don't like on the question is that ** everyone** will be willing to get rid of firearms. DPKR is good example where limitations on warfare had no effect at all – Pavel Janicek Dec 6 '14 at 9:31
• @DavidMulder have any limitations on types of warfare been successful? Any restrictions that come to mind - chemical weapons, cluster bombs, land mines, etc have all been used many times after a "consensus" that they should be restricted. Furthermore, for any such restrictions the policy of the major power on "X is bad, don't use X" has been either (1) we don't use X, since we use Y that does it as good; (2) ok, we won't use X but we'll be ready to use X if we really really need it; or (3) we won't use X but we'll use nuclear weapons to retaliate if it appears (e.g. US policy on biowarfare) – Peteris Dec 6 '14 at 17:09
• Idea for how the premise could work: aliens have become disgusted with the warlike tendencies of humans and banned large sections of weapons. The aliens have advanced surveillance technology and will immediately kill anyone who uses a ranged weapon. – ckersch Dec 6 '14 at 18:30
• Again. 80% is far from "everyone" and that's where I have problem – Pavel Janicek Dec 7 '14 at 7:49

Any such rules against range weapons would be ignored. In a battle, your goal is to take any unfair advantage over opponent and kill him. It is not about fair play.

Chemical weapons were banned because chemical weapons do not give one side clear advantage, killing often your own soldiers when wind shifted, and otherwise maiming mostly civilians. See that nuclear weapons were not banned, because they do give advantage.

Also, it would be impossible to remove all existing range weapons. It would be huge incentive to keep secret stash, because it would give you huge advantage over any opponent attacking with only a melee weapons.

And when you are fighting for your survival, you are not interested in fair play.

If you think that any rules apply in the fight of survival, you are naive and will be eliminated - only non-naive will survive long-term.

Different matter are staged fights for entertainment or ritual reasons - like box, judo, medieval jousting. Even mixed martial arts do have rules - because it is a sport, not real fight.

• I would argue that the following of these "laws" would depend on the enforcement capabilities, if a few dozen large world governments jointly owned a super-weapon capable of instantly incinerating anyone from space and enforced the ban on ranged weapons with this I think it would be far more possible. The OP didn't make it clear that people willingly obey the law, just that they obey it. – Vality Dec 7 '14 at 2:53
• There is no such thing as "jointly owned super-weapon". Explain me how USA, China, Russia and EU would "jointly own" such thing. Whole point of such super-weapon is to make its ownership to be exclusive to allies, and exclude opponents. Only naive would believe that superpower would share. Yes, they may promise - but why to share is you can own it exclusively? There are always conditions to be added to anyone who should share such weapon. – Peter M. - stands for Monica Dec 7 '14 at 18:47
• And if you know your opponent is developing such weapon, the only rational response is to strike before it exist, while you still have a chance. Mutually-assured destruction. – Peter M. - stands for Monica Dec 7 '14 at 18:48
• Once a while my answers gains downvotes (with no comments), because it breaks someone illusions about war, and maybe martial arts as "real" fight. Oh well. Life is not fair, and then you die. – Peter M. - stands for Monica Apr 14 '15 at 0:06

I'll assume that trivially abused technologies such as hammers or chain weapons with rocket engines and shaped charge impact weapons are also banned. Same with chemical and biological weapons.

There also some important parameters unspecified in the question. Is it socially and legally acceptable to carry visible lethal weapons? Is duelling legal? Really, this is three questions: Optimal visible weapon to carry for self-defense AND duels. Optimal hidden self-defense weapon. And optimal formal duelling weapon. Of these the last two could really be anything depending on the legal and social parameters so I'll assume you are not interested in those.

For the first, I'd go with a sword. Swords have a tradition value that just cannot be beaten. And for a good reason. Unlike a gun that can be used for lethal damage or threatening with lethal damage, a sword can attack OR defend well, and even gives a degree of control over the damage you cause.

What kind of sword? Well, one reason "a sword" is an easy answer is because there is a sword for every need waiting for you in the history books. Some parameters: Is use of body armor allowed? Do the restriction s apply to actual wars or just peacetime use? From the question I am guessing you expect the restrictions apply during wars (unrealistic IMHO). That would imply needing a sword with reasonable armor penetration. A society like this would probably use augmented or powered armor. (Augmented = takes care of the weight of the armor, no power source strictly necessary; Powered = adds power source for enhanced strength and speed) With modern materials either could be essentially immune to small arms level damage. Explaining why the ban has a chance?

With those parameters a fast precise thrusting weapon with armor piercing point would seem optimal. That is generally called a rapier. With powered armor the rapier would probably be shorter and heavier. The weapon would be of modern alloys, corrosion resistant and almost impossible to break or bend. The tip, possibly the entire blade, would have hardened surface of something like diamond, sapphire, or silicon carbide, whatever is most convenient. There is no real point in giving the weapon enhancements for penetration as it is easier to improve thrusting strength mechanically at the armor. Even a light weight peace time street armor would have more space for enhancements than the blade does and give all the benefits of a heavy swung weapon but with better speed and precision.

It might make sense to give the blade an incapacitating attack after penetrating armor. Either an electric shock or a chemical injection of something like capsaicin would be simple enough to do, fair enough to be allowed, and quite effective at ending the fight. Which otherwise would be an issue with a weapon that is essentially an armor piercing point with some range. A hand-guard would be present obviously.

For off-hand I'd go with a shorter version of the same blade injecting less instant but longer lasting tranquillizers into opponents that you have temporarily incapacitated with the longer blade. Would also give more flexibility to melee range and be useful for parrying. As an alternate weapon maybe some sort of simple chain weapon for entangling the opponent?

And I suppose this would scale to "mecha" on battlefield, tanks and such being of limited use without cannon. The blades would be driven by high speed hydraulics and inject binary explosives. And the mecha might have four or six legs, probably with wheeled drive available.

The biggest change would be that without missile weapons, or some equivalent that would be equivalently banned, aircraft would be unstoppable. Troops could be rapidly and easily dropped anywhere in range, kept supplied, reinforced, and extracted. Ground warfare would be dominated by relatively light easily airlifted elite units adept at hit-and-run and rapid responses to hit-and-run. Such units would be based on the same the heavily defended bases as the aircraft that transport and supply them. Defenses would include "siege units", larger, heavier versions of the light units as well as static defenses. Similar defenses would be present at other strategic locations.

• I think you'd see robot-wars / battlebots weaponry on tanks. Powered, armor-piercing rams; wrecking balls; weaponized heat-based cutting tools (torch or electric). – Peter Cordes Dec 6 '14 at 19:15
• @PeterCordes Not so sure. Frankly the effect on military vehicles is kind of difficult to predict. The problem is that guns are one of the biggest forces on the evolution of military vehicles over the last few centuries. Without guns all that would have to be rethought from start. A tank for example is a mobile platform for guns with heavy armor to protect it from guns in a form factor designed to be harder to shoot at. Without guns? Yes, tanks would still be scary and could carry all kinds of weapons, they already do, but is that what people would actually do? I have no idea. – Ville Niemi Dec 6 '14 at 19:32
• I posted an answer of my own where I thought some more about things. Out-manoeuvring the enemy vehicles to reach an objective is much easier when they need to completely catch you to do anything to stop you. But I think you'd see bulky tough vehicles for defending the area right around important objectives. You're right that they wouldn't be used in anything even resembling tank vs. tank warfare. (although now that I think of it, I don't have much idea about how to use a force of tanks. I just know the names Rommel and Patton, not much about how they fought.) – Peter Cordes Dec 6 '14 at 19:40
• @PeterCordes Edited the last paragraph of my answer, largely due to your comments. – Ville Niemi Dec 6 '14 at 20:40
• @PeterCordes LOL, you actually pinpointed something that I could not solve when writing that new paragraph. How would you win or lose a war in this setting? Or would wars as we know simply vanish and be replaced something akin to modern special ops? No idea... – Ville Niemi Dec 7 '14 at 18:17

I'm going to say energy weapons will become the next great wave, light sabers/ion blades etc. Things that can cut indiscriminately through as many materials as possible.

One movie years ago had a villain that had a 'laser' thumb. His bionic thumb had some kind of ion cutting rope/string that acted like a small whip. but if it wrapped around anything it would cut right through it. Of course he died at the end when someone took his thumb and wrapped it around his neck.

If light isn't considered a 'projectile' then laser guns would be a big one on the docket. Chances are it would happen anyway whether legal or not. Quiet, invisible, are to trace.

Axes and pole-arms are good, don't need a lot of training to at least be useful.

Had another idea which I think those of us in the US would go for, sending in robots in our place. They aren't projectiles, but they do remove us from the action...

• It's 2014 right now and the best projected energy weapons we have that run on hand held batteries are pretty paltry (in terms of potential damage) to say a house hold hammer. – Culyx Dec 5 '14 at 17:42
• @Culyx I'd personally would go with an ax, if I could get a nice battle ax your in business. – bowlturner Dec 5 '14 at 17:44
• Agreed, something with a blade and a "pick axe" style protrusion for harder armor, best of both worlds – Culyx Dec 5 '14 at 17:45
• I think you are talking about Johnny Mnemonic. The weapon in question there is a Monomolecular Whip ( en.wikipedia.org/wiki/Monomolecular_wire )..the idea is that you make a strand out of a single molecule then it would both be extremely sharp and extremely strong, able to cut through virtually anything without resistance. – Tim B Dec 5 '14 at 20:38
• @TimB That's it! I honestly wouldn't have thought that was the movie. I'll have to watch it again soon. Wasn't it like a whole "2 gigs" of data they needed to write into his head? – bowlturner Dec 5 '14 at 20:43

You're looking for mechs, aren't you? Most advances in melee weapons that I immediately think of are going to be powered devices with several drawbacks for the common soldier. They will be heavy, they will need a power source, and they will have inertial issues that make them prohibitive.

That is unless you connect them to a frame with its own power source, has enough mass to handle the torque and inertia and mechanical assist to deal with the weight of the weapon. So, you need basically a mech. They'd start off human sized or slightly larger, but that would escalate quickly. You'd have melee weapons like chain-swords, probably with a blade nearly white-hot. I personally like a Jaws of Life style weapon made to peel back enemy armor like tissue paper. Artificial Intelligence assist would be a must, leading to more arms with more weapons.

Armor meant to turn back a knife blade would be a secondary concern since your primary concern would be an EMP. This soldier would fail entirely if it wasn't armored in essentially a farady cage.

• Actually not @mechs, ksmarts answer was the direction I was originally thinking of more, but fair enough :P – David Mulder Dec 6 '14 at 3:28

People don't carry personal weapons much any more; before firearms in Europe people carried rapier-like weapons, so those would probably return (albeit with slightly lighter and stronger blades due to advances in materials science). Swords are great weapons for civilian use: small enough to not get in your way most of the time, but almost all of the weapon is dangerous.

For wars--good grief, who would ever? Just drive cars or something into the enemy. Bus vs. pikemen = a bunch of dead pikemen. Bus vs. halberdiers = dead halberdiers.

This is all assuming you could even enforce such a law, which seems doubtful outside the context of alien occupation or some similarly vast technological gulf. (And then I don't think the lack of guns would be most people's first concern.)

• +1 for Bus vs. pikemen. literally loled. But yeah, a car is just a special case of the tank / powered armor that people would end up using. – Peter Cordes Dec 6 '14 at 19:08
• @PeterCordes - Powered armor is hard to do with modern tech (near-future now, perhaps, but it's not usefully here yet). Vehicles of all sorts, yes. Still, war is pretty awkward when you have to literally drive over your opponents. – Rex Kerr Dec 6 '14 at 20:46
• Vehicles can have a good variety of 'almost-ranged' weapons - i.e. captive bolt or extending spike variety weapons that allow a devastating kill at some limited but useful reach. – Peteris Dec 6 '14 at 21:59
• @Peteris - To some extent, but armor is strong compared to spikes (just watch old episodes of RobotWars). You mostly want to flip/crush, not puncture, because your opponent can just put a foot of reinforced steel around the whole thing, which is pretty much impenetrable to non-explosives. – Rex Kerr Dec 6 '14 at 22:17

I would suggest this kind of sword

The blade is split in 2 halve. In the center, you have an explosive charge and an accelerometer.

When the blade hit something (a piece of software make the difference between a block and a hit) the charge explode adding much power to the blow.

Of course, you add a repeating system.

Better materials I'd guess.

The dune saga might be a good starting point - projectile weapons were obsoleted by technology development (in that case, shielding that worked against fast moving projectiles resulted in a culture where bladed weapons were common. There's one case where they used artillery on planet, and it caught everyone by surprise).

Not counting magic forcefields - You might have low cost, ubiquitious , non newtonian materials for body armour (or even normal clothing) that could negate fast moving weapons. Maybe energy Point defence may work against larger projectile. In short the only way to penetrate that would be slower weapons.

Its worth considering millennia of better materials development. Consider significantly better materials, and metallurgy. Better ways of working on those materials as well.

Consider the Japanese Katana - A sharp hard edge, with a strong flexible core. You might have a diamond or ceramic edge, and a composite core instead of folded steel.

You'd also have better bows and crossbows - maybe autoloading servo actuated crossbows or electrical/electronic scopes to adjust for drop and wind speed for better accuracy. Arrows would be composite instead of wood and you could balance these precisely and fire them with much more consistent force

You'd have weapons optimised for certain roles. Explosive arrows for anti material roles or getting past hardened body armour, or specific weapons types for stabbing or tearing through 'soft' body armour, or assisted for punching through hard exoskeletons - maybe low speed, high pressure spike for hard exoskeletons for example.

Without ranged weapons, but with modern vehicles for transportation, you won't have a "front line" of fighting. Your enemies can drive or fly right up to your headquarters, and try to do whatever raid they have in mind.

Your HQ will have to be underground, or someone will fly up to it. 3 dimensions is too much to defend. You need to cut down access to your base to one dimension, through an access tunnel that your enemies can't just overwhelm or blitz.

If your enemy comes at you with transport helicopters full of guys, you can't just shoot them down, unless energy weapons are allowed. You'd need fighter aircraft to defend anything. Aircraft could try to tangle other aircraft in cables, or stick things into their engines or props / rotor blades. Short of kamikaze attacks, you could maybe make a personal-delivering missile with an armor penetrating nose. This counts as a vehicle because there's a guy inside it. He may have to fly it for this to work vs. your alien overlord lawyers enforcing this rule, but ok. So you fly your missile into the enemy plane, open a hatch, get out and wreak havoc. Hope you brought a parachute or jetpack.

As far as weapons go, personal weaponry might include variations on the captive bolt pistol, which has the advantage of not being muscle-powered. Those who aren't up to using swords might get more out of a powered spear. (captive bolt rifle = longer reach = spear).

And of course just running people over with vehicles will make it probably not viable to be an un-armoured combatant on a battlefield. Robot-wars tanks are the likely result of evolution of vehicular combat. Mecha maybe worth building, if they're better at stepping over wreckage. Because you have to be up-close and personal to fight at all, more fighting might happen near the objective. Without range, it's harder to stop your opponent just going around you. (or impossible, really, since they'll use transport helicopters.)

They could use powered exoskeleton. The suit is powered with small, high capacity batteries and can enhance the strength and speed of the soldier. It could be something similar to Iron man but with less advanced technology. They might be able to fly somehow, for short distance or more likely jump at great distances.

Eventually, some might decide to alters their body to become a cyborg: half man, half machine. They would do this to have an advantage in the battles or to replace severed limbs.

An army could also use robots but in that case nobody is fighting since everything is done by the machines. Robot fights could even become a source of entertainment and \$.

I think one version of 'powered' weapons would involve taking the mechanisms of projectile weapons and applying it to melee attacks. Imagine a war hammer that has a 'magazine' of high density fuel charges (something similar to the propellant used in rockets) that can be 'fired' to suddenly accelerate the hammer head toward the target.

There are no projectiles and a semi-automatic firing system would allow the wielder to deliver rapid heavy blows limited only by the balance/recovery (weight?) of the total weapon.

The other 'firing mechanism' similar to the above would be an impact trigger, landing a blow would trigger the fuel and a second high acceleration blow would follow the first blow.

Armor is largely limited by weight, enough armor can stop large directed impacts (like a pick axe) but the armor needed is heavy when thick enough to do this. I think this style of fighting would largely favor agility (not getting hit) as opposed to absorbing hits.

• I was thinking along those lines, too, a weaponized version of the captive-bolt cattle slaughter thing Javier Bardem killed people with in No Country for Old Men. – Peter Cordes Dec 6 '14 at 19:17

I don't know if the physics would support it, but I'm imagining some sort of hand-delivered shaped charge. Something like a powerhead, only bigger, and without a launchable bullet.

With the rise in heavy armor that would come with the removal of firearms, something like this would allow an unarmored person to still be a threat.

1. Lightsaber or energy/ion/plasma/lightning melee weapon.
2. gunsword or a hammer or lance with blank rounds at the tip. The explosive rounds at the end could detonate when hitting the opponent, to add explosive or armor piercing damage. Same as a powerhead, with the muzzle blast being the damage dealer.
3. Energy intensive objects, such as ultra high-speed gyroscopes that can be swung to cut the opponent.

The premise of why projectile weapons would be eliminated is the biggest influence on development. Generally speaking, rules do not apply to existential threats - I don't find it at all plausible that someone would just stand around helplessly while their friends and family are massacred and their entire civilization destroyed because they cannot use better weapons against a stronger opponent. You still want a world with warfare, rather than some pacifist utopia, so you will need some overriding reason behind people not using any projectiles - this will need to be so overriding that it must be specified before determining the direction of military development, which will be entirely shaped by your restrictions and the enforcement thereof.

For example, if you just want some tenuous physical connection, what about TOW missiles? They are anti-tank missiles which are still connected to the operator by a thin wire. This may meet the letter of the law and loopholes like that would allow the side with the most creative justifications to completely dominate.

If you want to restrict things to purely physical weapons (no explosive assists, pneumatic bolts, etc.), you are probably going back to soldiers wielding something like a bec de corbin and wearing heavy plate (albeit with modern alloys and synthetic fibers). With assists, a penetrating captive bolt war hammer or spear might be the favorite. Modern armor itself would be practically immune to most physically powered hand-held weapons, so impact weapons to kill through sheer concussive effects would be most prevalent.

Powered armor to greatly boost the strength of a soldier might give someone an edge by better penetrating armor, but the weak-point is still the soft fleshy thing inside it getting killed by the impact. Vehicles will probably dominate as they can carry better power and keep the driver protected from impact - running down individuals and ramming each other as best they can (maybe even modified jet powered craft hovering over troops to injure them with the hot exhaust).

Of course, soldiers meeting on the battlefield at all is unlikely unless you also rule out motorized transport to get around the defending soldiers to attack wherever. No way you could reliably defend against aircraft inserting enemy shock troops into your capital/factories/infrastructure without projectiles. Warfare becomes hit-and-run guerrilla tactics to force the collapse of your entire civilization.

If you are thinking about energy weapons, there is no plausible means of a human-carried power source being able to deliver nearly enough charge that even simple armor could not defeat. How far out do you want to go on the 'fantasy/unreal' end of things - if you are going to throw out the laws of physics to get things like lightsabers, or plasma whips, or whatnot, just go all the way and say they use a magic staff (magic also explains why there are no more projectiles, which is otherwise an implausible eventuality).

Everybody obeys these laws

I think that under certain historical conditions, you could get almost everyone to obey such laws. Say that there had been a war so grotesque, destructive, and genocidal that it engendered global revulsion toward the weapons that had enabled it (anything that lets you kill someone from a distance without them being able to fight back). Using such weapons would be seen as akin to raping a child, something even other criminals, as a whole, aren't likely to let you get away with. It wouldn't be the laws per se holding people back then, rather it would be simple moral consensus. However, that won't stop absolutely everyone.

Even more money than in the last 14 years was spend on weapon development, so weapons can be a bit fantasy-like/unreal from our perspective.

You can really go anywhere with that. Electrified whips, as someone mentioned, lightsabers, chainsaw-axes, powered exoskeletons for extra strength so you can hit people really, really hard with your morning star, ferraris with poisoned lances in the grill, all the way down to rocks and boards with one nail in them.

• We can't even get the population to obey road speed limits. – Oldcat Dec 16 '14 at 19:06
• I don't think the impetus for speed limits is analogous to the scenario I suggested – Aurast Dec 16 '14 at 20:47
• If someone was coming to kill your children, would you just attack the killers with a pointy stick despite knowing it was completely futile, and resign yourself to your family being slaughtered? How about your entire civilization? I know I would pick up a gun and try to save them - 'moral consensus' notwithstanding. – pluckedkiwi Dec 17 '14 at 14:16
• Being law abiding citizens, most people wouldn't have projectile weapons to defend their families with. As for someone trying to destroy your civilization, that is a situation where such weapons would probably be used. But destroying a civilization is a very unusual goal in warfare, particularly in modern times. We've gone close to 70 years of near constant warfare now without using nuclear weapons. – Aurast Dec 17 '14 at 15:09

The RPG 'Rifts' used technologies such as 'vibro-swords, vibro-daggers' and the sort. The idea was relatively simple...a blades edge could be brought to vibrate at a quick enough resonance and at an atomic scale, allowing the blade to vibrate through regular materials at an absurd rate, severing the bond of any material it was cutting through at a microscopic scale.

For weapon development, a lot of these technologies would actually descend through medical research and development...exceedingly precise incisions is always a need in a medical setting. Taking these medical innovations and powering them up to larger scales is where the weapon developers come in.

If only melee weapons were allowed, depending on how that was accomplished, I'd imagine that air superiority would become an even greater thing. Sure, you have a nice line of tanks. I can just fly over them, or drop things on them (nets, rocks, delayed explosives, chemicals, localized EMP). You're attacking me with an impregnable mech, I'll just fly into your base and take it over.

Even taking out an aircraft could be a pain. If the melee only tech was some sort of high velocity neutralizer, good luck trying to hit a jet. And without missiles of any sort, welp...

Electrostatic whip with varying degrees of lethality that can stun, wrap around and magnetically ensnare, crush, electrocute or completely sever torso's of enemy combatants at intermediate range. Think railgun whip. Can also be armour or vehicle mounted used to attach, to reel in and used in conjunction with other powered cutting devices

Reach will be key. We can easily create more lethal melee weapons, the real question would be how to deliver them to their opponent. I see people developing very long, quickly extending weapons that are almost like short-range weapons. For instance is the modern taser, which shoots out two wires that stay attached to the taser a melee weapon? can people create increasingly innovative versions of these?

of course that's for home use, the more interesting question is what the government uses. There is still no reason to arm men with your 'standard' melee weapons, people die too easily. Powered armor is generally impractical, it's easier to stick with modern tanks. Create increasingly more complexly armored tanks, with increasingly lethal attachments designed to cut through the enemies armor. Then run the two tanks into each other and see who can cut through the others armor the fastest.

Of course cutting THROUGH armor may be impractical. Maybe they will simply heat the enemy tank up enough to kill the pilots inside with heat. Maybe they will prefer faster tanks to strike slow tanks and build up electric/heat to roast the pilot inside. It really comes down to rather one can build armor or weaponry faster.

Of course the real answer is that guns will still be made and used regularly, because criminals, by definition, don't follow the law ;)

I crossed a Medieval knight's lance with my car's extending antenna and using high powered hydraulics, made it so that it can extend at high speed. Now, whenever I turn on my car's radio, I can immediately impale things 10 feet in the air. I like to take my car to the woods. If the antenna doesn't get the squirrels, the music will.

I call it the Turbo-Lance.