I haven't, and I've never taken a class. Why? I've "played" with knives my whole life. Beleive me, having it in your hands every day teaches you everything you need to know about using it. How to hold it comes naturaly with holding it. A cook does alot of cuts, requiring many different holds. all one has to do is put the two together, I wanna cut this guy in this way, 1+1 = slit. Add to that a potentialy unstable Jarhead psycie that may or may not have dreamed of that moment his entire professional life, he gunna kill Jodie damnit, gunna kill'm good. That being said, stabbing some one who jumps you is so easy a blind one-armed monkey with downsindrome could do it. Offing the shotgun was rather impressive though, he's got kajones.