Sorry, it's all a bunch of useless nonsense built to take your money. IMO. If you carry any knife for self defense, you're not carrying enough ammo. I love my knives, don't get me wrong. But I'd be just as likely to look to jab a ballpoint in someone's eyeballs as pull a knife if I was unarmed. Being able to pull a knife fast is great.. if you're within arm's reach of the bad guy.

Ninja videos are great... entertainment.