Posts: 3,361
Threads: 411
Joined: Nov 2014
Reputation:
25
Time Played: 5,461.47 Hours
Level: 442
Rounds Played: 5,559
Not all weapons can be leveled. The ones that can are called "Enhancable" items. You can usually tell if it can be enhanced in the description, or if all the stats are at their lowest values, or if you right click it and it has an 'enhance' option.
Enhanced items require a variety of things to gain XP.
Some of these specifically say inside the description, while others let players figure out exactly how to do it. Most of them are simply just normal kills, however, I'm looking at possibly changing this entirely to make ALL of them level off of killing, with the current 'unique' methods of gaining XP, changed to bonus ways to gain XP.