Anyone playing with live knives on a regular basis is either insane or an idiot. There are so many safer alternatives that it just makes no sense whatsoever. [/b]
Yeah, there's a story I was told about a demo in our club (years before I was there, different sensei to now) where a live tanto was used. Flew out of somebodys hand during a block and hit the face of a junior student in seiza. Luckily it was the flat of the blade, ie cut not maimed.