rusty bubbles:
You have my sympathy over the rising crime in what has been one of the great cities in the Western world. It's not your fault, but let's see what you can legally do to protect yourself.
Any tool that multiplies force (hammer, large wrench -- spanner?, pry bar, etc.) can be used as a weapon. They are, of course, also of use in many households. We keep a small ball peen in the kitchen drawer, for example, to hang pictures and for other tasks (the hangers are in there, too). It would, however, be an extremely potent weapon, especially with the round part of the hammer head as the striking surface. Claw hammers with straight claws are quite vicious, too.
One of the meanest (yet invisible) weapons I've seen in a home is a large, square, heavy glass ashtray. You don't need to be a smoker: you're a good host and may have a guest who smokes (even if you ask them to carry the ashtray outside with them). Grab one corner and strike with one of the other corners. The heavy ashtray could do a lot of damage, yet it can sit on a table in plain sight. You could even throw it at an intruder. I'd put one in every room.
Oven cleaner and poison for killing wasps and hornets are both useful. The insect spray that we buy is a foam and has lengthy warnings on the can about eye damage. It can be sprayed several feet with fair accuracy. A faceful of that would be quite horrible, I imagine. We keep it around because the wasps have built nests on the side of our house. I've destroyed maybe a dozen nests in the past few months.
A light chair is a great weapon, if used with enthusiasm and aggression. Hold the back and jab fast and hard with the legs. Very difficult to block or avoid. If you're strong, you can throw it. Marc "Animal" MacYoung once observed that there's no good way to catch a chair.
I like a cane or a small flashlight in public. Look for yawara or kubotan information on the Web to find out how to use the light. The Mini MagLite was designed for this use. I'm fairly young (45) and healthy, but I've had injuries, and I carry a cane when out on foot. If my knee or ankle acts up, I'll need it to get home. I don't fake a limp, but I don't run or wave the cane around or anything. In the politically correct 21st century US, no one dares ask questions about a disability, but I'm ready to talk about my knee pain. A plain, sturdy, one-piece, crook-top cane is probably the least likely to cause suspicion.
Never forget books and metal clipboards. They can be used for both blocking and striking, yet no one seems to notice them. Not ideal, but a surprise shot to the face with the edge or corner of a book or clipboard would hurt!
Cups, mugs and bottles can also be used, as can full cans of food, soda or beer (though I'd hate to waste a good beer). The 8-ounce Coke cans that are sold here are fairly easy to throw. A few cans in the bottom of a heavy cloth shopping bag could be very effective.
It's all about momentum and striking surfaces, such as corners or edges. If you look around, almost anything is a weapon. I hope this helps.
Best wishes,
Dirty Bob