First, your non-lethal self-defense weapons should be simple to use, lightweight, legal to carry, and above all be effective.
Essentially anything can be used as a weapon, and keep in mind any weapon can be lethal, as well. A blow to the head using a rock, a punch to the face, or a stab with a pen, or even a shock from a Taser can be lethal. The weapons and methods described here would be considered, under normal circumstances, non-lethal by definition.
Stun Gun
Some states and local municipalities regulate the sale and possession of stun guns or Tasers and a few states ban them outright, illegal to have one in your possession in other words. Generally, they are legal to have in states that do not have specific regulations, if carried for self-defense purposes. In some cases you may be required to purchase one from a licensed firearm dealer. A Taser or stun gun is considered a non-lethal device, and they are very effective in subduing an aggressor.
One downfall when using a stun gun is that you have to make physical contact with your aggressor. A Taser will fire probes, so you can subdue a person without them getting close enough to grab you, while a stun gun uses prongs that must make contact with a person. If attacked and you are grappling with an aggressor than they are ideal for stopping the attack immediately.
Tear Gas/Pepper Spray
Keep in mind Mace is simply a brand name, but for the purposes of this article it will be used to indicate so-called tear gas products. Mace is essentially tear gas, usually called defense spray, and the name Mace may be associated with other products such as certain pepper sprays.
Some find that tear gas or a derivative of tear gas, which is available to civilians, is not as effective as pepper spray when it comes to personal defense. Mace is generally used to control large crowds or to force someone from a structure/room, and is used often by law enforcement and the military.
Mace is classified as an irritant, while pepper spray is classified as an inflammatory. Pepper spray has an immediate effect on most people, and generally will incapacitate an assailant. Tear gas available “over the counter” usually does not have an immediate effect on those intoxicated or under the influence of drugs.
There may be restrictions on the concentration of the active ingredient when purchasing and there may be restriction on where Mace or Pepper Spray can be purchased. If there are restrictions then they would usually have to be bought from a licensed firearm dealer or even from a pharmacist.
Baton
Typically, you can carry a baton in the absence of criminal behavior. What this means is that you cannot carry one with the intent of committing a crime with one. We will leave it there for you to decipher.
Some states and local municipalities however, do restrict the possession of one, so check first. However, generally they would be allowed, as would a walking stick, or even a tire thumper used to check for soft tires. You can purchase collapsible batons that would make carrying one easier, and you can ever buy collapsible stun batons. A stun baton extended would prevent an assailant from making physical contact with you.
Tactical Flashlight
Most tactical flashlights are equipped with a striking bezel that can be used for self defense. Some models are also equipped with a blinding strobe feature that can disorientate an attacker. When gripped in the fist a metal or even a hard plastic flashlight can be used to pummel the head and face or other parts of a body. Grip one in your fist as if you were going to pound on a door.
Tactical Pen
A heavy metal pen can be used to stab any part of a body. Usually they are sold as tactical pens, but any pen for that matter would work to some extent. Metal is of course sturdier, and metal is recommended for self-defense purposes. With metal you would get greater impact and penetration.
Other Items
A purse, satchel, or briefcase can be swung at an assailant, and while they may not do much physical harm, the distraction may be enough to allow you to escape.
Your car keys can be used by slipping a key between your fingers as you make a fist. This gives you a metal object for stabbing/punching the hands, head, or face.
As stated earlier, essentially anything can be used to defend yourself, but the best case scenario is to always have an item on your person that can be used. You probably would not find too many rocks or pieces of two by fours lying around a store’s parking lot late at night, so you do need something close at hand.