I'm thinking of adding a particle beam underbarrel attachment.
The idea is that the device powers up over time as the user figures out ways of increasing it's power. As they explore the world ways of increasing its power come to them in dribs and drabs. The way this works is the device does 3D6 MD base damage, but has a percentage chance (starting at 50%) of doing an extra 2D6 damage. You roll during initiative - if you pass, it does the extra damage for the rest of the combat (until it's ammo runs out - it can do four shots a day. Costs 50 credits a shot). I'd go 1D6 extra damage, but I don't think 1D6 is terribly impressive.
Anyway, so now instead of having to put some kinda new weapons in every nook and cranny they explore, or somehow giving them a new weapon for figuring out stuff in the world, I can tell them that percentage increases by one or two points! Thus slowly making the weapon more powerful!
When it gets to 100%, it resets back to 1% and the weapons base damage increased by 1D6 (3D6 goes to 4D6).
Though this kinda means a step backwards in power as when the percentage is 90%+ they'd probably be getting the +2D6 extra damage, well, over 90% of the time. But when it upgrades, it's as if they go down by one die because at the start your going to have a very low percentage and rarely roll it.
Not sure what to do about that. As said, I could just make the bonus 1D6...but it doesn't seem alot. I'm certainly not having the base damage increase by 2D6!
I guess a mitigation (but not solution to that) is to not have it reset to 1% on upgrading, but to 50%. But I want this mechanic to stretch, giving about 2% every ten minutes of play. It'll cut back on that alot if I do that and it still doesn't really solve the problem.