The best self defence weapons are the ones that are effective repelling an attacker, easy to use and convenient to carry. There is no single self defence weapon that is best for every situation. Some work well for self defence in the home while others are better for self defence while you are out in public. You must consider the pros and cons of each weapon for each situation.
A firearm is the most powerful self defence weapon. It requires very little strength or training to use and inflicts lethal force. Most American adults who do not have criminal records and do not have a history of mental illness can purchase a firearm and keep it in their home. If you are willing to take firearm safety courses, use a trigger lock to keep it away from children and use reasonable restraint shooting it, a firearm is good self defence weapon for the home. You should not carry a concealed firearm in public unless you have a special permit allowing you to do so.
Mace and pepper spray are non lethal self defence weapons. They work best for people who get basic training in their use. An attacker must be sprayed in the eyes for the chemicals to work most effectively. Practice with the spray is necessary to get the aim right. You must also keep the spray bottle in your hand and ready to use when walking around potentially dangerous areas. If you are willing to do these things, mace and pepper spray are good self defence weapons.
Any hard object that extends your reach makes an effective weapon. These include sticks, clubs and batons. Makeshift weapons like heavy flashlights, umbrellas and walking canes are also useful. They can be swung at vulnerable points on an attacker's body. Attackers usually attempt to control a victim with their upper body. A firm strike the attacker's lower body can stop him instantly. Swing for the shins, knees or groin. When the attacker doubles over in pain, whack him over the head. A stick is an easy to use and effective self defence weapon.
A small knife, used properly, can be a good self defence weapon. The knife must be small and portable. The blade must be easy to draw so that you are not fiddling to open it in a crisis. The user must also be trained in its use. The knife should not be flashed as a threat. It should be a surprise quick strike weapon to jab or slash suddenly. When the attacker is stunned you should run away. Movements with the knife must be simple and deliberate. Slicing the hands or other exposed skin accomplishes this. Penetrating flesh or cutting through clothing is much more hazardous. Knives should only be used by those trained to use them.
Some of the best self defence weapons are things you already carry around with you. The best places to strike an attacker are the vulnerable areas of his body. A heal to his toes, keys to his eyes or finger nails to his cheeks will stun him for several moments. This may be long enough for you to get away. A whistle, a mobile phone or a scream can alert others to the attack and frighten the attacker away. These are not technically weapons but consider using in a threatening situation.