The way UK defines "offensive weapon", literally anything is one if you have intent to use it against somebody, even in self-defense:
"any article made or adapted for use for causing injury to the person, or intended by the person having it with him for such use by him or by some other person ... even if they have some other legitimate use e.g. car keys held between the knuckles"
It is illegal. It probably does sound insane if you believe that carrying weapons can improve safety and not simply escalate violence. To me it’s a pretty sound policy.
