The quick answer is that the knife itself is legal, but how you carry it matters.

What 3.5" blade length, scafool? There's no reference to blade length in the Criminal Code, and a couple of months back I searched case law for any reference to blade length and found nothing. Is that just a local guideline? Do you know something I don't?

Dean, Canadian law for knives is actually very relaxed. The only laws specific to knives are those that prohibit automatic knives, any knife that opens by centrifugal force or gravity, and push daggers.

Other than that, knives are covered by general laws on carrying weapons. There are three provisions that really matter:

1. a weapon is anything designed for use, intended for use, or actually used to harm someone or intimidate them.
2. you may not carry a weapon for the purpose of committing an offence or causing a breach of the peace.
3. you may not carry a weapon concealed, period. (There's a provision for concealed firearms permits, but that doesn't apply here.)

So as you can see, everything hinges on whether the knife is a weapon, which is a matter of its design, your behaviour with it, and how a cop and the courts interpret your intent.

If you have a clear reason to carry that knife, e.g. carrying it openly while hunting or fishing, or carrying it home from the place of purchase, there would be no problem. Carry that same knife concealed in downtown Toronto, with the stated purpose of cutting string and tape, and you'd be in trouble.