How far can you stretch your weapon laws over there? What about hammers? What if you had a hobby as a carpenter and every time you go into town you buy a hammer so you have a receipt on you to explain why you are carrying a claw hammer on the tram. And then when trouble arises, you can strike the villain in the base of the skull with the hammer rendering him dead instantly by crushing important parts of where the spine connects to the brain. By killing your enemy in a single strike, by surprise, you mitigate the risk of being sliced slashed or stabbed by a knife.
I would also practice throwing my hammers in the back yard every day, until I can very accurately destroy a watermelon at 20 paces. And then I would throw my hammer at the attackers face.