A defensive weapon is a personal weapon that is primarily intended for defending the user against an attacker. The most prudent way to avoid injury in an attack is to foresee it and avoid it. Since this is not always possible, defensive weapons must, to be effective, be small and light enough to be carried easily; if they are not, then they will not be carried, and will be absent when needed. They must also be ready for instant use, since attackers are generally not going to make their intentions known ahead of time. Often the mere presence of a defensive weapon will discourage a criminal attacker; they will avoid the armed victim and choose a safer, defenseless target.

Ancient defensive weapons

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Throughout most of history, the dominant defensive weapon would have been a club of some sort. With the advent of the Bronze Age, the defensive weapon of choice became a dagger or sword. These were small and light enough to be carried in a sheath worn by the user, and could be quickly drawn in case of an attack. With the changes in metal technologies and personal armor, the sword evolved to fit the needs of the user. In Europe, this was the usually a rapier or similar item, while in Japan it would be the katana.

Modern defensive weapons

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Firearms

"God made all Men, Samuel Colt made them equal."

--popular saying from the late 1800s

With the advent of the reliable handgun, the sword began to fade in importance as a defensive weapon of choice, although there was a considerable overlap when it was not uncommon to see sword and pistol worn at the same time. With reliable handguns, the range of the defensive weapon moved from roughly twice the arm's length to dozens of yards or meters. Apart from its range, another redeeming factor for using a handgun as a defensive weapon is that its power is largely independent of the strength of the user--it depends on the power of its cartridge, rather than the ability of the user to swing a heavy club or blade. The advent of the revolver, which allowed multiple, rapid shots before reloading, signified the final demise of the sword. The transition from single or two shot pistols to repeat-firing, five or six shot revolvers may well represent the greatest advance in civilian defensive firepower that has ever occurred. A modern expert could easily hit a man-sized target from 50 yards (46 meters) with a handgun. Still, the handgun is primarily a defensive weapon. Compare the handgun to a sniper's rifle, which is used as an offensive weapon, and can be used to engage targets at ranges of over a mile (1.6 km).

"...no law enforcement officer should ever plan to meet an expected attack armed with only a handgun."

--"Handgun Wounding Factors and Effectiveness", 1989, FBI

When portability is not an issue, such as defense of a vehicle or dwelling, a common choice for a defensive weapon would be a riot shotgun. Being larger, a riot shotgun is aimed far more easily than a handgun, and the ability of the shotgun to fire multiple projectiles per shot makes the probability of obtaining a debilitating hit on an assailant much higher. Shotguns also give the option of using special ammunition, such as rubber buckshot or rubber bullets, that turns a shotgun into a less-than-lethal weapon, or shotgun slugs, which turn the shotgun into a short range rifle, with acceptable accuracy out to over 100 yards (91 m). A carbine or submachine gun is also a common choice in the military, for troops not directly involved with infantry combat. Police also often carry a carbine, such as a short AR-15 variant or a Ruger Mini-14, in their vehicle for situations where a handgun lacks the power and accuracy needed in a situation.

Less than lethal defensive weapons

Stun guns have been available for many years, in the form of small, handheld devices, batons, and projectile forms, such as the Taser. These deter an assailant by interfering with muscle control, and by inflicting pain. The small handheld versions require close contact with an attacker, and are of very questionable use as a deterrent due to the low voltages they use. Batons and Tasers are often more powerful, and allow a greater distance from the assailant, but in both cases they are quite bulky and the higher voltages they use, while increasing effectiveness, also increases the risk of lethal injury. Riot control agents such as pepper spray and tear gas have been available in forms suitable for self defence since chemical Mace first became available in 1962. These disable an assailant by temporarily blinding them and causing severe pain. Since these agents are delivered in aerosol form, range and accuracy is dependent upon environmental contitions, particularly wind. Use on an assailant attacking from upwind, for example, can result in incapacitation of the user as well. Chemical agents have widely varied effects on different individuals; while they can disable most people for a short period of time, others can tolerate them well enough to continue an attack. Often drugs that increase the user's threshold of pain will allow an assailant to overcome what would normally be dehabilitating effects of the chemical agent.

Despite their limitations, less lethal options are an attractive alternative to lethal force for self defense for many civilians. Unfortunately, they are also heavily regulated or outright prohibited in many areas. See the sections on riot control agents and pepper spray for more information on use restrictions.

Less lethal weapons, while not as reliable at stopping an attacker as a handgun, are still used by most police departments. While their use in warfare is prohibited by the 1924 Geneva Protocol prohibitions on chemical weapons, they are often used by militaries as a chemical weapons simulation. In addition to the traditional riot control use, chemical agents are used by police to help apprehend or subdue suspects who are not posing an immenent threat to life, but are resisting enough to risk injuring an officer. Like rubber bullets, their use has come under fire in recent years due to a number of deaths they have caused or contributed to. It is for this reason that the term non-lethal weapon is falling out of use; any weapon capable of disabling a person is also capable of causing death, even if only indirectly (for example, a mugger who is disabled next to a subway track might fall and be crushed by a train).

Personal weapons