When you think about kenjutsu study in classical times we think about all the different styles practising without wearing bogu and using bokuto. Starting about a 100 years ago various schools started to use men, kote, and dou. This allowed for more freedom in practise and was a way to train your body, polish your techniques, and had the advantage of allowing you to strike each other amongst other things.
This was a lot different than the classical period method of practising where – if you went too far – you could cause injury to yourself and your opponent. Due to this there was also an element of fear in this type of training. As you move you can sometimes strike strongly even though the movement was light, or strike lightly even through you thought you were strong. Practising armour-less with bokuto becomes very hard without a sufficient understanding of this matter.
Amongst classical kenshi there were not a few that had inter-school matches (taryujiai) using habiki (blunt metal blades) or bokuto. In these matches there were countless people beaten senseless or even killed. For those of these that called themselves masters, causing injury to others seeking to follow the same way is shameful. In normal practise you don’t aim to injure your students after all. However, for those of us that study the way, we should not be stuck in set shapes, but be able to respond to various changes in our opponent, and we cannot say that we always control our strikes.
Advanced people showing the way to those with less ability is the way of heaven (i.e. its natural). There is no room for argument in this point. If thats the case, then why is it that people who do the popular armoured-shiai (the most popular term at the time was gekkiken) only strive to win? In that world its natural that there are winners and losers, yet isn’t it the case that those that are of higher ability feel no danger (even when armour is not used) when they are fighting?
In the case that you do have an unarmoured shiai, please understand the value of the sense of the danger you feel and use this when you wear armour and fight.
In a unarmoured shiai, if a kenshi full of vigour is attacking someone more skilled than they are and they attempt to fight as if they are using armour injuries will definitely occur. If you think about this point deeply, and do some research, it may be possible to conduct armour-less shiai without injury. (Editors note: I do not condone this)
Someone who causes injury or death during a armour-less shiai cannot call themselves someone who follows the True Path of the Sword.
Yamaoka Tesshu, Meiji 17 (1884), January.
山岡鉄舟：剣禅話 。徳間書店.高野 澄(翻訳)