I got back into transcendence, (again), and I notice there's still a lack of illegal weapons. (Note that I've not yet bought Eternity Port or Corporate Command, since I don't have a job at the moment and therefore I'm stopping myself from spending money)
So lately I've been working on a mod to fix that, and just ran through my first (cheating) game with them to test balance. (And there's almost nowhere to install them, so I learned nothing!

So far I've got two lines of illegal weapons: the counterfeits, and the 'ommidrectionals'.
Counterfeit weapons, ("K22 Morningstar Laser", "Luminous Particle Canon", "Dual Recoilless Thermos Striker", etc.), are chinese-knockoff style weapons, (none of which are the damage type their names would suggest). On installation, they roll 6d500, and 1500 or less is a timer on shots fired until they blow up, leaving you blind & with depleted shields, (and damaging the weapon).
My balance scheme right now is to price them a tech level lower, and give them a tech level higher damage (and energy usage), to make them tempting enough to use.
Fluff & graphics, they use fireworks to appear to be different damage types, which often involves me playing around with the graphics until I get something that looks silly. Lasers headed by a pellet and leaving a smoke trail, a particle beam with an explosion at its tip, etc.
The 'ommidrectionals' don't try to violate trademark, they just shoot in every direction. Not like an omnidirectional weapon. But like 6 kinetic canons glued together mounted on the bottom of a ship. ("Normal particle weapons are linear accelerators directed at the enemy. This is a ring accelerator which appears to have 'weapon ports' hacked into it with a knife").
They're also linked-fire.
They have the same timer as the counterfeits, but only damage themselves afterwards.
When I've cheat put them on a starter ship, they felt pretty useful for clearing out swarms of sandstorms, or coming in close to a enemy station and clearing out all the small stuff.
I know their damage & cost is off, but not having found anywhere to install them, it's hard for me to judge whether to make it go up or down. 6/8/12 shots normally would 1/6th, 1/8th, 1/12th the damage, but because the shots are all around the ship and all firing within a random 1/xth of a circle, it's impossible to aim at one ship with all shots, and very hard to aim at any particular ship with any shots. Currently I have it set at 1/3rd, 1/4th, and 1/6th tech level damage, to make up for the random chance of breaking.
Currently, I also haven't put the work into making my timer variables unique per install, so each weapontype shares the same timer. So 3 installed omnidrectional kinetic cannons, for example, would all run down the same timer 3x as fast and all break at once. (This also means you can try to game it by frequently uninstalling and reinstalling any of my illegal weapons. Which makes fluff sense, readjusting the weapon and whatnot). I'm not too concerned about making unique timers because I can't seem to find how to make variables persist across saving/loading anyways.
Now, I'm obviously going to have to expand my mod to include places to install illegal weapons and devices, so I have three things in mind I want to add while I'm at it:
1) Counterfeit Luxury Items
Direct copies of things in the game, but with the 'counterfeit' tag on them, which will operate much like the illegal tag with respect to seizing and whatnot, (if it's easy to make that happen), but can be sold, at the normal price of the items they clone, to commodities exchanges. (Instead of the maintainence shop, or victorian nightclub). Provided one has a smuggler's hold.
2) Counterfeiting Manufactories
I haven't decided yet whether these will be moving ships you can dock at, (probably use the graphics from the salvager nomad), but they'll be much like the existing manufacturing stations. They'll only sell counterfeit goods, primarily the luxuries, will be able to install illegal weapons and devices, and will need a black market ID chip. I haven't even so much as thought to look at it yet, but I'll need to figure out how stations make things vary in price and how cheaply I can get them to sell the counterfeit goods.
I'll probably have them buy stuff like radioactive waste, hydrocarbons, and other suspicious stuff to need to be making 'terran eggs' and the like. I might have to make a few extra normally unsaleable items, just to be disgusting.
3) A 3rd weapon line
My original idea for counterfeit weapons was literally two or more ordinary weapons jammed together, but I couldn't figure out how to make one weapon shoot multiple types of shots. Now that I've found and successfully used the sysCreateWeaponFire function, I think I just need a counter in <OnFireWeapon> events to run through two or three different sysCreateWeaponFire's. I'm not totally sure how to cut off the normal weapon fire if I want them to alternate, but for the most part I'll be wanting the weapons to fire at the same time anyways.
I think the timer damage for this one will simply be causing it to stop firing after some time, (until reinstall) . . . it doesn't make fluff sense that perfectly safe weapons made by reasonable manufacturers wouldn't have safety features to stop firing before being damaged or damaging the ship they're on.
I don't have a balance scheme for this yet, because I'm not sure how having multiple weapon types from one weapon will be yet. I usually pilot an EI500, so it sounds amazing to me. ("I can have one weapon that very few things will be completely strong against?!"), but other ships like the Wolfen might be more 'meh' towards it.
Since I'll be drawing from existing vanilla-transcendence weapons, I'll also be wanting to apply bonuses from devices and such, and I haven't looked in that yet.
That's . . . already quite a bit, so I'm putting my other ideas to the side for now, but I also want to expand on illegal shields & illegal devices sometime in the future. I have no ideas yet on those could possibly be reasonably illegal, but I'm sure I'll come up with something.
(And somewhere down the line, I want to take advantage of the fact that the amount of stuff in your hold effects how fast your thrust can move you, making a light ship with barely any thrust, a high top-speed, and a lot of cargo room. So as you fill up your cargo, it becomes increasingly difficult to maneuver. Of course it wouldn't be able to install any engines least of all the ineratialess drive. And sometime else down the line, I want to work on side & rear facing weapons, which could have interesting balancing difficulties, as that would allow you to fire while fleeing or while circling respectively)