A chain saw that shoots that cold frosty chemical that starts with an N but I don't remember the name allowing it to freeze stuff and grind it to little bits!
Or this weird Idea I had with grip that has three chains coming out of it and one chain has a katana, one has a claymore, and the last has an bunch of razor blades put together in a ball that when slammed against something split up and then pull back together using MAGNETS..
You know what lets just take the last item that sounds pretty cool...
Just like drop a bunch of razor blades and have the handle consistently pull them all back to it... Could even make em electrical or something... It works like a normal mace usually but when you twist the grip the magnets all off or on O_O
Oh another one, this is more of a property for a close quarters weapon I think would be cool, but when its activated it slows down time of all physical mass within a 10 foot radius to 1/10 speed, the only thing not effected is thought, slow motion combat. *momentum still has just as heavy a pull, it basically just makes all people within ten feet able to see all the actions of that messy close quarters fight with ten times reflexes
The reverse would also be awesome, A thousand thoughts of death and split second