True BEAR deterrent spray, not self defense pepper spray
UDAP Pepper Power Specifications, Spray Ranges and Pricing
I was fooling around with some cops I knew, one as* let off the pepper, you need to be sprayed to understand. It doesn't just burn, it blinds and constricts your airway to the size of a tiny straw and you can't suck enough air to continue a "battle''
All in all, these ideas everyone is posting, most will freeze when confronted by an aggressive robber at night, most of the rest will have their "self defense" weapons taken away and used on them. Surprise is NOT on your side and that wins most initial battles.
If I was going to carry anything other than a gun it would be a collapsible metal baton, those suckers will do some damage and often the "snap" as they deploy will scare an intruder away (I'm not talking a perp with gun or knife, give them what you have if they are armed with lethal weapon) Make sure you get a police/military grade baton, some of the ones sold on the net are about as strong as one of the old automobile collapsible antennas, the real ones lock and extent into each section enough to form and almost solid steel bar and you can get ones with knobs on the end for added weight and "destructive" capability
If I carried anything myself it would be the good old 30" oak nightstick, in the hands of someone who knows how to use it , prodding and pressure points not swinging like a bat, that things is murder, Not too inconspicuous though
Or you could learn to box
seriously, mental preparedness is the number one choice for self defense