Here in the United Kingdom you can get sent to prison for carrying any offensive weapons.
This includes ANY firearm, any imitation/replica firearm, a fix-blade knife with a blade over 3" long, mace/pepper spray and just about anything anything else that you could possibly think of.The UK government has a zero tolerance on any offensive weapons.
Now in order to still carry an item that could possibly save your life I recommend using something like a high powered torch with a strobe. This little torch will give you valuable seconds to make an escape from an potential dangerous situation.