Here's what some of our laws say about what is allowed and what isn't. Quoted from a book called Canadian Law and Self Defense:
PROHIBITED DEVICES
All of the following are prohibited devices in Canada:
and, while it is true that all these devices are prohibited, this list falls short of ALL the devices that have been prohibited by Order in Council.
Some of the missed things are knives.
Prohibited Weapons List:
• any device designed to be used for the purpose of injuring, immobilising or otherwise incapacitating any person by the discharge therefrom of
(a) tear gas, mace or other gas, or
(b) any liquid, spray, powder or other substance that is capable of injuring, immobilising or otherwise incapacitating any person;
• any instrument or device commonly known as “nunchaku,” being hard non-flexible sticks, clubs, pipes or rods connected by a rope, cord, wire, or chain;
• any instrument or device commonly known as “shuriken,” being a hard non-flexible plate having three or more radiating points with one or more sharp edges in the shape of a polygon, trefoil, cross, star, diamond or other geometric shape;
• any instrument or device commonly known as “manrikigusari or kusari,” and any similar instrument or device, being hexagonal or other geometrically shaped hard weights or handgrips linked by a length or lengths of rope, cord, wire or chain :
• any finger ring that has one or more blades or sharp objects that are capable of being projected from the surface of the ring;
• the device known as Taser public defender being a gun or a device similar to a gun capable of injuring, immobilising or otherwise incapacitating a person by the discharge therefrom of darts or any other object carrying an electrical current or substance, or any other similar device;
• any device that is designed to be capable of injuring, immobilising or otherwise incapacitating a person or an animal by discharging an electrical charge produced by means of the amplification or accumulation of the electrical current generated by a battery, where the device is designed or altered so that the electrical charge may be discharged when the device is of a length of less that 480 mm, or any other similar device;
• any device commonly known as a Crossbow, with a stock of 400 mm or less, or any other similar device;
• the weapon known as the “Constant Companion,” being a belt containing a blade capable of being withdrawn from the belt, with the buckle of the belt forming a handle for the blade;
• any knife commonly known as a Push Dagger that is designed in such a fashion that the handle is placed perpendicular to the main cutting edge of the blade;
• any device having a length of less than 30 cm and resembling an innocuous object but designed to conceal a knife or blade, including the device commonly known as the knife comb, being a comb with the handle of the comb forming a handle for the knife;
• and any other device similar to the device described as the constant companion, the push dagger, but not including the aboriginal “ulu” knife, and the knife comb.
• the device commonly known as a “Kiyoga Baton” or “Steel Cobra” and any similar device consisting of a manually-triggered telescoping spring-loaded steel whip terminated in a heavy calibre striking tip;
• the device commonly known as a “spiked wristband,” being a wristband to which a spike or blade is affixed or any similar device;
• the weapon commonly known as the “Yaqua Blowgun” being a tube or pipe designed for the purpose of shooting arrows or darts by the breath, and any similar device;
• the device commonly known as a “Morning Star” and any similar device consisting of a ball of metal or other heavy material, studded with spikes and connected to a handle by a length of chain, rope or other flexible material;
• the device known as the “SSS-1 Stinger” and any similar device that consists of a single shot weapon of any calibre and is designed or of a size to fit in the palm of the hand or in a cigarette package and
• the device known as “Brass Knuckles” and any similar device consisting of a band of metal with finger holes designed to fit over the root knuckles of the hand.
As for what is legal to carry...on the whole, Canadians are allowed to arm themselves with a weapon for self defence (except a firearm), if the weapon is suitable to the danger anticipated and is not carried concealed and you do not beg from nor accost or impede anyone while carrying it or go to a public meeting.
So carrying a big obvious belt knife is pretty much the only thing you're safe with...but if you use it and a judge decides that you used more force than was needed to neutralize the situation (another part of the law that is WAY different than in the US), you could be charged with assault, aggravated assault, or murder even though you were only defending yourself...it's happened many times.