Airway.. i was referring to the throat.
give yourself a tap on the throat. its fragile. easy to hurt, and easier to drop an opponent by hitting it. too hard an they will die from lack of oxygen, moderate impact crumples them. its hard wired into the brain to panic when the throat gets hit. try it next time. knife edge chop is a fast carrier of doom.
if the odds are against you, dont use strength or pain to deter your opponent. if they are crazed, pain wont affect them, so use vital strikes.