Kendo and self-defense
Kendo is, among other things, a martial art. Naturally, martial arts are often connected to different ways of self-defense. Here are some simple fact about Kendo:
It is a full contact sport.
Armor is necessary because shinai can do serious damage (even mortal in the case of an unfortunate hit to the face/throat region).
It has it's roots in centuries old samurai fighting styles that were designed primarily to kill quickly and efficiently.
Although all mentioned previously is true, Kendo is still pretty much useless as a form of self-defense.
This may seem odd. How can a sport/martial art that uses full contact sparring be irrelevant in a potentially dangerous situation?
There are several reasons, big and small.
First of all, Kendo is practiced only with swords: bokken and shinai. Both can inflict injuries, especially the sturdy bokken, but people usually don't carry wooden swords with them. Even if one did, most attacks like muggings and brawls take place in a matter of seconds and in close quarters. As a martial art, Kendo does not put emphasis on aggressive response and pain tolerance, which are valued in many self-defense technique and/or full contact martial arts. The goal of Kendo matches isn't to do as much damage to your opponent or to incapacitate him. Although Kendo increases awareness, this will only help in recognizing potentially dangerous situations, not in dealing with them.
The sad thing about self-defense in general is that only experience in this kind of situations can help you; experience that was learned through pain. Street fights and similar events are equally about how much pain and damage you can take as well as deal out. Of course, all of this is only relevant to bare hand fights. Don't forget knives, screwdrivers, bottles, bricks and guns that are also ever present.
If you want to learn how to defend yourself - take up Boxing, Judo, Krav Maga or one of any other numerous martial arts of fighting technique. But remember: it's always better to avoid violence altogether.