Nah... what other item takes up two body slots? ...eh?

I like it. If a +3 rock is to overpowering in your campaign, Machete, you havn't sat at a table with me: I've had monkeys throw gaurds at a fullplate clad dwarf fighter, and knock her out! I know one player who wants a pair of these to throw gaurds back...

Your presentation could go with a touch up, but otherwise, the items themselves are fantastic, double price and all (I think this is the balancing factor)! Good idea.