Section 2 of the Criminal Code includes the definition of weapon:
“Weapon” means any thing used, designed to be used or intended for use
- (a) in causing death or injury to any person, or
- (b) for the purpose of threatening or intimidating any person
and, without restricting the generality of the foregoing, includes a firearm.
Proof of an item as a weapon depends on all of the circumstances. The determination involves a subjective test of whether the accused intended to use the item as a weapon. 
R. v. Cassidy,  2 SCR 345 cites R. v. Chalifoux  states weapon includes:
- anything designed to be used as a weapon;
- anything that a person uses as a weapon, whether that thing is designed as a weapon or not; and
- anything that one intends to use as a weapon regardless of its design.
The decision of R. v. D.A.C., 2007 ABPC 171 proposed a general analytical approach to determine whether an object is a "weapon" under s. 2. The Court must "ask the following three questions:
- i. Did the accused in fact use the object to cause death or injury, or to threaten or intimidate any person?
- ii. Did the accused intend to use the object to cause death or injury or to threaten or intimidate any person?
- iii. Was the object being carried by the accused designed to be used in causing death or injury to any person, or for the purpose of threatening or intimidating any person?
If the answer to any of these questions is in the affirmative, the Crown has proven that the object was a weapon." The third question was considered in greater detail. The judge stated that the test for determining whether the object was designed to be used requires the following questions:
- Is the object’s design such that it could be readily usable to cause death or injury to any person or to threaten or intimidate any person?
- In all of the circumstances, would the carrying of the concealed object cause the reasonable person to fear for his own safety or for the public safety, if he were aware of the presence of the object?
If the answer to both of these questions is "yes", then the object will be considered a weapon. This requires looking at the object itself and the context of it being possessed.
Carr A, Ory D (2006). "Does HIV cause cardiovascular disease?" PLoS Medicine, 3(11):e496.
The Criminal Code distinguishes "prohibited weapons" and "restricted weapons" as subclasses of "weapons" generally. Additional weapons-related offence apply to those weapons classified as "prohibited" or "restricted".
“prohibited weapon” means
- (a) a knife that has a blade that opens automatically by gravity or centrifugal force or by hand pressure applied to a button, spring or other device in or attached to the handle of the knife, or
- (b) any weapon, other than a firearm, that is prescribed to be a prohibited weapon;
Before anything can be a prohibited weapon it must first be established as a weapon under s. 2.
Under section 4 of the Regulations Prescribing Certain Firearms and Other Weapons, Components and Part of Weapons, Accessories, Cartridge Magazines, Ammunition and Projectiles as Prohibited or Restricted, SOR/98-462, provides:
The weapons listed in Part 3 of the schedule are prohibited weapons for the purposes of paragraph (b) of the definition “prohibited weapon” in subsection 84(1) of the Criminal Code.
Part 3 of the Schedule, Prohibited Weapons, Former Prohibited Weapons Order, No. 8 states:
1. Any device designed to be used for the purpose of injuring, immobilizing 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, immobilizing or otherwise incapacitating any person.
2. Any instrument or device commonly known as “nunchaku”, being hard non-flexible sticks, clubs, pipes, or rods linked by a length or lengths of rope, cord, wire or chain, and any similar instrument or device.
3. Any instrument or device commonly known as “manrikigusari” or “kusari”, being hexagonal or other geometrically shaped hard weights or hand grips linked by a length or lengths of rope, cord, wire or chain, and any similar instrument or device.
4. Any finger ring that has one or more blades or sharp objects that are capable of being projected from the surface of the ring.
5. Any device that is designed to be capable of injuring, immobilizing or 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 than 480 mm, and any similar device.
6. A crossbow or similar device that
- (a) is designed or altered to be aimed and fired by the action of one hand, whether or not it has been redesigned or subsequently altered to be aimed and fired by the action of both hands; or
- (b) has a length not exceeding 500 mm.
7. The device 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, and any similar device.
8. 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 and any other similar device other than the aboriginal “ulu” knife.
9. 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 similar device.
10. The device commonly known as a “Spiked Wristband”, being a wristband to which a spike or blade is affixed, and any similar device.
11. 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.
12. 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.
13. The device known as “Brass Knuckles” and any similar device consisting of a band of metal with one or more finger holes designed to fit over the fingers of the hand.
The mens rea for offences regarding prohibited weapons, it need only be proven that either knowledge or recklessness with respect to the characteristics of the knife in question which, in fact, makes it a prohibited weapon.
The test for establishing a weapon as prohibited is an objective one. The Crown does not need to prove that the possessor of the object "used or intended to use" the object as a weapon.
- R. v. Murray, (1985), 24 C.C.C. (3d) 568 (“Murray #1”) - spiked wristband found as weapon
R v Murray, (1991), 65 C.C.C. (3d) 507 (“Murray #2”) - nunchaku sticks not proven as weapons
- R. v. Archer, (1983), 6 C.C.C. (3d) 129 at 132 (Ont. C.A.)
- R. v. Strong, 2012 BCCA 279 at para. 35
“restricted weapon” means any weapon, other than a firearm, that is prescribed to be a restricted weapon;
- R. v. Boutilier  4 W.W.R. 443 (B.C.C.A.)
- R. v. Labrecque, 2011 ONCA 360
Under the Ontario Prohibited Weapons Order in Ontrio No.8 SOR/79-583, brass knuckles are classified as prohibited.
The crown must prove that the holder of the brass knuckles used or intended to use the item to cause death or injury to persons or intended to use for threats or intimidation.
The intent must be proven subjectively and objectively.  - References
- The following devices are hereby declared to be prohibited weapons:
(b) 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.
-  O.J. No. 405, 12 W.C.B.(2d) 487 (Gen.Div.)
- S.(L.B.),  S.J. No. 512, 21 W.C.B. (2d) 279 (Q.B.) - case uses new definition of weapon under s.2
Where a knife is used to intimidate, it becomes a weapon.
- R. v. MacDonald (2002), 170 C.C.C. (3d) 46 (ONCA)
In certain courts, bear spray has been established as a weapon. It is usually necessary to have forensic expert testimony.
- R v Meier, 2012 SKPC 41 at 101
A broken piece of glass can be a weapon.
A vehicle can be a weapon.
- R. v. Allan (1971), 4 C.C.C. (2d) 521 (NBCA)
- see R. v. McLeod, (1993), 84 C.C.C. (3d) 336 (Y.T.C.A.)
R. v. Lamy, 2002 SCC 25 (CanLII),  1 S.C.R. 860