Weapon Proficiency is what it sounds like, as in becoming more proficient with weapons by damaging things. Damaging someone(player/bot/vehicle) will add a little bit of "proficiency", and killing someone(player,bot,vehicle) will give a bigger bonus.This can be done with a weapon set/single weapon if its impossible to script.
Weapon level 1:Untrained
The gun has more spread than its default value(ex. Default gun now has spread, even though it had none before this addon.).
Weapon level 2:Trained
Half the spread when firing. (Spread on gun X now has 1/2 the spread it has when untrained.)
Weapon Level 3:Marksman
The weapon now has its original spread(Default gun no longer sprays everywhere when you shoot, for example.)
Proficiency should reset on death. Why weapon proficiency? Because you can't just pick up a gun with no training and snipe someone with it.