Well, I for one am full of dumb ideas.
Weapon 1: The Blessed Mallet of Saint EEEEUUUUUWWWW!!!! from a Munchkin expansion: Deals extra damage to zombies and makes them flee for a few seconds when it hits
Weapon 2: The Fart Gun, based on the Fart Gun from Despicable Me, probably uses Sound_Fart (one of the only legit uses for this sound pack besides whoopee cushions), perhaps a greenish-yellowish-brownish smoke cloud with longer range than the sword but not by a whole ton, would incapacitate+injure or even kill players within the radius, Killing yourself with your own fart gun possible. Along with that, perhaps a clothespin item that would, when used, clip over a player's nose and make them immune to fart gun damage, but can be knocked off with a headshot from even nonlethal-headshot weps.
Weapon 3: A weapon much like the broken Darkness spell that would instead stun (paralyze) players for a few seconds, or even just fix Darkness by covering up the client's screen with black when they have been hit. Some coding could be stolen from Rotondo's Zombie Mod Boomer (which covers the screen in white when killed at close range).
Weapon 4: A Healing Magic spell that uses up energy but heals the amount that it uses up. Use Jet to heal another player, normal click (and hold) to heal yourself. Cannot exceed target's max HP.
Weapon 5: A Handguns Akimbo. Enough said.
Weapon 6: A two use thrown weapon: Shoe. First use is right shoe, second is left. Rather weak but funny.
Most of these are not gonna happen anytime soon, I'm afraid...