[Zelizz]

I took a self-defense class where we practiced using improvised weapons against a few simulated actual weapons. Against a short knife, a sweater wrapped around the arm was not very useful (but better than nothing). I much preferred a long stick, with which we would maintain distance and strike at the hand, and a chair, which makes a handy, pointy, shield. Against a knife, I'd rather have an umbrella than a sweater, jacket, or nothing.

Important to note, though: The class stressed that your best option was to have enough money on you to satisfy your attacker. A mugger who just made $100 is much less likely to beat you to death for spare change.