What does 'know what he's doing with a knife' really mean to you? Does it mean he's some high level, ranked and frocked grand mufti of some system? How about just a big, angry man with no formal training, and murderous intent, who's stabbed people before, and who's single driving desire is to run you through? Do you think some formal 12th degree black belt in knife-fu-do somehow trumps that? I think we do ourselves a disservice to believe that 'formal training' equals superior skill. The knife is a simple instrument, and it doesn't require complicated training to utilize effectively. Push the knife in, pull out, repeat as needed as rapidly and powerfully as possible. Here's a good example of how that really looks.... Oh, and this is a good wakeup call....<warning: not for the squeemish' Notice the REAL knife attack at the 1:45 mark......what style of martial arts do you think he was using? http://www.youtube.com/watch?v=k5LQ5ddZ_b0&feature=related Now, there are some who've commented on knife defense 'Oh yeah, i'd just use my kung-fu parry and then crush his trachea with my knife edge hand strike'.....ahuh..... You should watch how REAL knife attacks occur, and train accordingly. Why do we show prison knife attacks? Because someone who has been in HERE is who you're going to run in to on the street if you ever find yourself confronted by a knife! It's as fine a 'dojo' for knife attacks as you'll ever see! And keep in mind that the largest mass-murder in US history was committed with box-cutters......the human mind is the weapon, and it's ability to apply tools in violently destructive ways is only limited by his imagination, creativity and desire to destroy! Never underestimate the 'other'.