[How it would benefit the server]: I think that weapon skins would be cool as they would show you achievement with that weapon, i.e if someone has got 250 kills with it then they will be granted an ok looking skin but if someone has like 1000 kills with a weapon then they will get a badass looking skin)of course there would be multiple skins that after being unlocked you could chose from) I think this would be a good idea as it would be a great achievement to get all skins and it would just make your guns look cooler in general, I know that I have got like 500+ kills with the Kriss vector already and I would like to see something new in the game just to brighten things up a little.
[Potential issues/exploits]: Possible it may glitch and not give somebody a skin when they reach a milestone but I don't see anything else.