It's dirty work, but somebody's gotta do it.

One of my Aunt's bits of advice was always to carry a can opener in your pocket. The ones that you use to punch holes in big cans of juice. It fits into your pocket discreetly and into your hand comfortably and with a quick lift of the hand that most likely won't be deflected because it looks like you are just flailing it gives a formidable weapon that will hurt them enough to possibly get away. If done with proficiency you can gut them like a fish. Granted this was a suggestion prior to mace and tazers but I still think it holds some merit.