Balisongs, switchblades, "gravity knives" and push daggers are illegal on the federal level. Assisted opening and spring assisted stuff is legal as well. A lot of stores will refuse to sell to you, though you are legally allowed to buy any knife on your own at literally any age so long as it does not fall into a prohibited category. If you want to pick up knives to carry or collect, you must:
A: Have a parent by them for you
B: Buy from a store that sells to minors (haven't run into very many so far)
C: (this is what I do) Buy over the internet/meet up on Craigslist. This forum in particular has a very good buy/sell section, though you have to be a paid member.
There are no length or feature restrictions besides the ones I have already stated, so it is legal to carry around blades of any size or appearance. However, you have to have a "reasonable cause" for carrying your blade; this does NOT include self defense. If you state your piece is for defence, you have broken the law and will at least get your knife confiscated. I generally state that my knife is for opening boxes, cutting open packaging, food prep, etc. These are all acceptable under Canadian law.
