Canada actually has very relaxed knife laws believe it or not (we can even board planes here packing smaller pocket knives). I believe the only place they're restricted is in drinking establishments due to the Liquor Control Act here.
The law generally views them as tools rather than weapons, unless they're used as such. But Canadian law permits us to use anything at our disposal to prevent grievous bodily harm or death, so a knife would be the most lethal tool that could be legally carried in public. I usually pack a blade, but not so much for defensive purposes, but moreso because they really are a handy tool. Not a day goes by when I don't have to open packaging with it, dig out a wood sliver, or use it for something!
Dog spray is not uncommon here either. I bought a canister for my ex to pack in her purse, which is probably the best less-than-lethal item we can legally carry here. As with knives, it can't be carried solely for defense against people (that would make it a weapon... verboten), but can be legally utilized against people should they pose a threat of bodily harm or death, if that makes sense. It's basically the 'law of necessity', which Canada recognizes, that allow us to break almost any law to prevent ourselves from facing grievous bodily harm or death.
Defense with a firearm follows a similar theme here, but due to the onerous regulations of possessing one in public (handguns particularly), most justified self-defense shootings here tend to occur in or on the homeowners property.
All that said, Canada is a fairly safe nation. There's very few places that I would feel unsafe walking through here. But as you say, we must remain vigilant of our surroundings. It's always best to avoid trouble if one can, rather than trying to convince a judge or jury that I feared for my life at a level that would justify me using force.
While our self defense laws certainly cannot compare with the 2A laws the US enjoys, it is also very, very rare for someone to be shot simply for wandering onto someone else's property here. Words and fists will usually settle most disputes here.