I know this sounds really funny (and I don't want to offend) but mine would probably be a whetstone with a knife, I am not a violent person but my only real talent is that I can sharpen a knife REALLY well.
I became a brony in march I believe, I was against bronies but being open minded I thought I should at least watch the pilot to say I've watched it and don't just hate for an excuse to hate 5 seconds into the pilot and I was a brony and regretted being a hater. : (