I carry a boot knife to fight off the ZOMBIES.I often considered carrying a potent Stink Bomb!
Not quite lethal, but it would keep those Gomers away at a distance for a time without riddling me with 7.62x39s.
Seriously, I gave my brother-in-law who is 71 years old, a small boot knife as a stocking stuffer this Christmas. I did it half in jest, and half for real. He loved it! (But he walks in a badass part of town, too.)