Legal self-defense tools apparently include bright flashlights / strobes (I kid you not) and personal alarms.
It's actually a pretty extreme doctrine, no? The UK does not enjoy a particularly low rate of assault or rape, compared to most other western countries. If unarmed self-defense is the only thing you can try, this would seem to put smaller-framed women, the elderly, and less physically fit people at a distinct disadvantage. Weird.
Additionally, anyone carrying a weapon is up to no good and can be arrested now. Do you know how often I carry a weapon? Never. I've never touched a loaded firearm (and I've been in the UK reserve forces for 15 years). I've never seen a firearm in the hands of anyone who isn't a trained professional (although if I lived in a rural area I'd probably see a farmer use one for vermin). I've never seen anyone with a knife bigger than a penknife (which mustn't lock) outside a kitchen or workshop, and if I did I'd call the police because they're up to no good. I believe that I am much safer than I would be if people around me were carrying weaponry.
You say it's weird. I think it's weird for people to wander around carrying weaponry. I know someone in the US whose brother considered taking a gun to the shops in case there was anyone there with a gun. Carrying weapons causes them to be used. When I go to the pub, do you know how often I wonder if the loud-mouthed slightly drunk guy is carrying a weapon? Never.
Casual UK knife crime (by which I mean the recent influx of stabbings etc amongst, typically, poor teenagers; not hardened criminals, but idiot, insecure children) is rooted in the unfortunate belief that they need to carry weapons to be safe.
Really? I'd take pepper spray over fists. I'm talking specifically about non-lethal choices, especially for people who do not stand a chance in a fist fight.
Most of Europe does allow pepper spray, stun guns, and similar tools, and they really don't see more violence than the UK. In fact, violent crime in the UK is fairly high in comparison with many EU states.