I'm with Bob. IMHO carry a folder for emergencies (any scenerio where a one hand opener would be useful) and a fixed blade for defense. We are talking about your life in a situation were you feel that a leathal response is justified. Do you really want to bank on a folder and your ability to deploy it? Me, I'd rather have a baton or maglight than a three inch folding knife no matter how well it locks up. Just my .02
Chet
Chet