Bow shouldn't be explosive, bow should be fire arrows, for a few reasons - 1) bug doesn't have enough guns, demo has plenty, and really doesn't need any more explosives 2) its more believable. I still like to think of KF as a survival horror game where people just found themselves in this situation and got lucky in finding guns at the traders, and fire arrows lend themselves to that better than arrows with C4 or something
Ideas - claymore: unlike the pipe, this can watch an alley and spray a shape charge, good for when you've got a door or 2 that need watching, but not as straight up powerful as the pipe (AKA, its not fleshie protection, but there to clean up those 4 clots that snuck in the back route). Would be tripped by ANYTHING that crossed its path, not like the pipes (They're based on the mobs mass right? gotta total over X before it goes off?).
throwing axes - similar to the bow, they have an arc to em, and you can only carry say, 3 to start and 6 as a max bezerker, idk. but they're fairly powerful, and can be collected. With these the zerker has a ranged attack that fits him, isn't overly powerful due to the skill it would take to throw and the ammo limit, and besides, it would be awesome to play with
Also - this would be a big project, but converting each gun and accessory to its own purchasable object so it's universally equippable. Kinda like how each gun in COD can have an RDS, or m203. Might spice up the equipping process, if its at all possible. Would take a crazy amount of work, and a new store layout, but it would be epic.