Wondering how to pick a self-defense tool? Use the APE test; Accessible, Practical, and Effective. A self-defense tool that is good enough for you or your loved ones must meet all three of these criteria before being selected as your tool of choice.
The simplest way to illustrate this interrelationship is a gun. A gun is effective. But a gun is not accessible (you cannot carry with you all the time) nor practical (local laws can make it actually illegal to carry a gun for self defense). Therefore, it does not pass the APE test and I would not recommend it as a self-defense tool.
Accessible—is the tool something that can be carried with you all the time. On your keychain, in your purse or pocket is accessible. If you have to keep it in your glove compartment or at home in a drawer, it is not accessible and is not considered a useful self-defense tool.
Practical—Is the tool something that is easy to deploy without special training or permits? Note that one should always train for self-defense, including the familiarization of your chosen self-defense tool. That’s not the training I am referring to in this case. I am referring to special training, such as the use of a gun. Also, a practical self-defense tool can be used effectively in a stressful situation? Key is “in the time of a stressful situation.” To meet this criteria, the tool should be deployable and used in an instinctive motion that does not require any thought.
Effective—Will the tool instantly re-direct the attack on you to self-preservation of the defender? An effective self-defense tool incapacitates an attacker long enough to allow you to escape. Strikes to the eyes, scratches to the skin, impacts on sensitive body points…anything that can do this, should be considered.