regarding krav and other 'self defense' nonsense... these people always say 'MMA is just for the ring, in the street there are no rules!!'
well, if you can't beat an MMA fighter *with* rules, what makes you think you can beat them *without* rules? trust me, anybody can eye gouge/headbutt/etc, but if you can't wrestle/control position you will get your shit pushed in by anybody who can.
and as far as learning gun/knife techniques, who do you think you are, chuck norris? a cast member of west side story? who gets in knife fights lol? that shit is for ponytail geeks who want to play army.
stick with the basics: wrestling, boxing, muay thai, and jiu jitsu. everything else will just make you think you can fight when you really can't.