unfortunately, i think this will inevitably lead to the buying and dropping of multiple melee weapons.
i understand your goal is to encourage the use of melee weapons other than the katana, but i think this just ends up hurting the zerker.
since the katana was introduced, there really isn't a reason (that i know of) to use any other melee weapon. it has good damage, fast rate of attack, fast running speed, light weight, and a relatively low cost. other melee weapons can't really compete.
i play zerk alot and mostly use the axe, not because it is better, but because i just prefer it. most other classes have some choices for their top-tier weapon, but with the chainsaw the way it is, if u want to survive on harded difficulties, you use the katana.
sorry, i'm going off topic. this is a nice idea, but in the end i think it does more harm than good for the zerk.