Strobing flashlights for self defence are very common, the problem they ran into years ago is that they can trigger seizures in certain people, usually not the intended target ends up un the floor..

There is lots of talk (of course) about this light right here:
www.candlepowerforums.com

More specifically, here:
http://www.candlepowerforums.com/vb/showthread.php?t=171440