I trained in martial arts for several year and we had a few sessions about defending from the neck chop... My conclusions: 1. Yes there is a nerve bundle in the neck that is a weakness but not one that is easily exploited in real fights. 2. That nerve bundle is VERY hard to hit properly. It is like hitting the 'funny bone' spot on your elbow. If you hit it just right it can make your entire arm go numb but it is such a small target and in slightly different positions on everyone such that it is not a practical target. Our teacher had to find it on each student with a little trial and error. It is not a tactic I think is viable in real situations. 3. It effects everyone differently. Just as some people have a 'glass jaw' and others do not... with the neck chop some people can just shake it off and some people crumple to the floor. 4. Just like boxing, and getting hit in the face, if you know what to expect you are better prepared. An experienced boxer can keep his wits and stay in the fight even if a specific hit made them see stars... same thing with the neck chop. Bottom line... If I get into a fight I am WAY more worried about getting hit in the face than about the neck chop.