Jonxlattheliom: yours pose 3 things. 
-your a freelancer, how would you fit that in with the origon of espionage. Cause if he is born durinf the war. Then he is build by one of the sides as there is no none type group. 
-you basically have 2 abilities (mimic looks. Copy weapon) and the copy weapon tends to be OP on the long run.

I know of 3 options for that.
-only take the mimic that can also makes a weapon look like the one he mimics weapons (though act the same as his normal weapon)
-only take the copy but it needs some limit (example: a memory slot that needs to over write one when taking on a new copy, a limit on how many times it can change during a day, it can take any but no heavy class weapons like rockets and super weapons and such)
also it cant take on any build in weapons like Drake his rapid 3shot weapon that is part of his arms)
-final one is something I guess you will rather want, yoi keep the mimic ability and instead of the copy you can have a weapon with multiple built in modes, like a shot gun. Assault rifle. hand gun. Grenade launcher. More can be added in time.
it limits yoir copy but lets you keep both in general sight