Bokken

Bokken
A bokken (木剣, bok(u), "wood", and ken, "sword"), is a wooden Japanese sword used for training, usually the size and shape of a katana, but sometimes shaped like other swords. Other common shapes are wakizashi and tantō. They are also known as bokutō (木刀, "wooden sword"), which is also the usual term in Japan.
These should not be confused with shinai, the bamboo sword used in kendo.
Usage
A bokken is used as a relatively safe and inexpensive substitute for a real blade in training for several martial arts. They are used in the early stages of training in iaido, when a practitioner has not yet reached the level where use of an iaito would be safe. An exception occurs when a certain kata involving two people is performed. Then the veteran teacher, or iaidoka, will use a bokken for safety. There are also specially designed bokken made for sword drawing. These are, for the most part, supplied with a plastic or wooden saya and are generally slimmer than a normal bokken and not suited for regular sword techniques.
Kenjutsu makes heavy use of the regular bokken in various drills, as does the Bujinkan and other Ninjutsu systems.
Bokken are used for the practice of kendo; to learn to make proper strokes and get accustomed to the curvature of the blade, as well as to practice the kata (forms). More than a few kata take advantage of the curvature of the blade and the presence of the tsuba, or hand guard, to block the opponent's sword. This is not possible with the straight "blade" of the shinai.
Many Aikido techniques are derived from use of the Japanese sword, although Aikido is primarily an empty-handed art. The focus of the bokken in some aikido dojo is not that of a weapon, but that of a tool to enhance focus. These wooden swords often have a smooth transition between handle and 'blade' and are not used with a tsuba. Other bokken are made to accept a tsuba and have a clearly defined transition between the handle and the 'blade'. Aikidoka practice a form of sword work known as Aiki-Ken that is slightly different from other Japanese arts. The bokken is used in Aiki-Ken to learn proper body placement and distance (maai) from the attacker, in an attempt to be in the safest and most powerful position. Philosophically, Aiki-Ken stresses the importance of moving into the safest killing position, allowing the Aikidoka the option not to perform the killing blow.
Construction
The quality of the bokken depends on several factors. The type of wood used, along with the quality of the wood itself, and the skill of the craftsman, are all critical factors in the manufacture of a good quality bokken. Almost all mass produced inexpensive bokken are made from porous, loose-grained southeast Asian wood. These bokken are easily broken when used in even light to medium contact drills, and are best left to work in kata only. Furthermore, the wood is often so porous, that if the varnish is stripped off the inexpensive bokken, one can see the use of wood fillers to fill the holes.
While most species of North American red oak are unsuitable for construction of bokken, there are some Asian species of red oak that have a significantly tighter grain and will last longer.
Superior woods, such as Japanese white oak, also known as Kashi, has been a proven staple, having a tighter grain than red oak wood. Another choice, hickory wood, seems to have a very good blend of hardness and impact resistance, while still having a relatively low cost.
The use of exotic hardwoods is not unusual when looking at some of the more expensive bokken. Some are made from Brazilian cherrywood (Jatoba), others from purpleheart, and some very expensive ones made from Lignum Vitae. Tropical woods are often quite heavy, a feature often sought in bokken despite the brittleness of these heavy and hard materials. Many of the exotics are suitable for suburi (solo practice), but not for paired practice where there is hard contact with other bokken.
Suburito are bokken designed for suburi. Suburi, literally "bare cutting," are solo cutting exercises. Suburito are thicker and heavier than normal bokken, and users of suburito have to develop both strength and technique. Their weight does, however, tend to make them poorly balanced; consequently, they are usually not used for paired practice or kata.
History
Historically, bokken are as old as Japanese blades, and were used for the training of warriors. Miyamoto Musashi, a legendary kenjutsu master, was infamous for fighting fully armed foes with only one or two bokken. It has been verified that he defeated at least one master swordsman in this manner; Sasaki Kojiro. Kojiro was armed with his "Drying pole", a long nodachi, but Musashi slew him with a bokken he carved from an oar while traveling on a boat to the predetermined island for the duel.