I don't know about Ontario (I saw a Canadian flag in your bio and didn't know beyond that) but they're illegal weapons in a lot of places even in the US, and Canada is worse about weapons.
Discussion
Yeah, in Canada you're basically not allowed to carry something with the intent to defend yourself. I didn't even think that it could be used as a weapon, to me it's just a decoration for my keychain.
It's a foolish rule and I know many who ignore it, especially in rural areas where predatory animals are a real and present threat.