Dougwalkabout has the right idea for a waitress at work. Using a weapon there in front of a crowd of witnesses, is going to be hard to justify and it's difficult to see how she could explain carrying a bottle or spray of anything while waiting tables.

Canada sounds like here in the UK, where you can't carry a weapon and that is anything manufactured, adapted or intended to be a weapon. Walk across the room and half way across decide 'I could hit someone with my pencil' and you became a criminal half way across the room.
Course if you are carrying something that could be used as a weapon but 'never thought I could use it as a weapon officer'. You are innocent. Admit you would use it as a weapon and you just admitted a criminal offence.
So a mini-maglite on a keyring (kubotans are for people who like prison food) a walking stick or umbrella, a long maglite torch in the car, lemon juice in a squeeze bottle 'because i put it in my tea officer' are not weapons. Use your imagination and check the law locally.
As P2CK says a few self defense moves. Peel their hand off your leg by grabbing the little finger and wrenching and they won't be keen to do it again.
The Sock