Another (pretty crazy) idea that just popped into my mind

What about a "Weapon Workshop" tab in Nexuiz where players can customize weapon parameters a little (of course between strickt limit). For example I have machinegun, and there are parameters:
- Spread
- Damage
- Ammo consumption
- Refire rate
And you can share points between it: you can make it damage more, but in exchange it looses from its refire rate and other stuffs like this. And the limit would be pretty strickt, but still could make some difference, like damage is by default 25, on max its 30, so the basic behaviour of the weapon wouldnt change much, just would feel more custom.
Or just one single weapon (a new one) that players can set together similar way.