Essentially the jyo is a wooden staff approx 128 cm in length. In modern times the measurements has been fixed to 128 cm in length and between 2.4 - 2.6 cm in width, though in the Edo-period the length of the jyo was customised as to suit the height of the wielder. The jyo is used in several martial arts such as Aikido and Tendo-ryu respectively.
The jyo, like its larger sibling the Bo, was never an effective killing-weapon on the battlefield in comparison to the sword, spear, glaive and bow. Although the jyo and most other staves could be used to lethal effect when thrust at vital points of the body, when faced with a fully armoured opponent those vital points would in most cases be covered by amour-plating.
With the onset of peace with the start of the Edo-period (1603-1867), the conflicts with heavy armoured warriors became a thing of the past. In this era, the jyo-art would come into its own against non-armoured samurai, ronin, bandits and other opponents. It was extensively used to police the local clan domains.
One of the most famous promoter of the jyo, was the founder of Aikido, Morihei Ueshiba.
The jyo was also adapted by Morihei Ueshiba, to teach the principles of aikido. His use of the weapon is called aikijo. Aikijo resembles jodo in that both involve fencing with the jyo, but differs in the nature and purpose of the fencing. Jodo techniques are often faster and sharper because angular attacks and defences are part of its combat orientation. Aikijo techniques are slower and softer because circular movements can blend with attacks and defences and reduce the attitude of conflict. Inserting and entwining techniques are not found to the same extent in aikijo as they are in jodo, nor are the numerous targets of atemi waza. Aikijo does have jyo-taking and jyo-keeping techniques, but these are aikido throws in which the jyo is incidental to the throw rather than essential to it.
Bokken
Tanto
A tanto ("short sword") is a common Japanese single or, occasionally, double edged knife or dagger with a blade length between 15 and 30 cm (6-12 inches). The tanto was designed primarily as stabbing instrument, but the edge can be used to slash as well.
Tanto with a blunt wooden or blunt plastic blade are used to practise safely. Also, versions with a blunt metal blade exist and are used in more advanced training or demonstrations.
Iaido
(Iai Batto-Ho)
Iaido is a Japanese martial art associated with the smooth, controlled movements of drawing the sward from its scabbard, striking or cutting an opponent, removing blood from the blade, and then replacing the sword in the scabbard. While new students of iaido may start learning with a wooden sword (bokken) depending on the teaching style of a particular teacher, many of those who study iaido use a blunted metal practice sword (iaito). Advanced practitioners of iaido use a sharpened metal sword (shinken).
Because iaido teaches the use of actual metal weaponry, it is almost entirely based on the teaching of forms, or kata. Multiple person kata do exist within in some forms of iaido, but the iaidoka (practitioners of iaido) will usually use bokken for such kata practice. Iaido does not include direct competition or sparring of any kind.
A bokken , (bok, "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, such as the wakizashi and tanto. Bokken is a term synonymous with bokuto in Japan, but is more widely used in the west.
Historically, bokken are as old as Japanese swords, and were used for the training of warriors.
Jyo
