Musashi insisted that one train with the long sword in the left as well as the right hand. If one's right hand is injured, must he die?
He also insisted that the Way is to wield the sword with one hand. Can one not hold the horse's reins and still cut? Can one not use both his swords?
Musashi wore his swords in the traditional manner, but he was not a traditional fellow. All that matters is to cut down the enemy.
I practice Hyoho Niten Ichi Ryu with Iwami soke who is 11th successor to Musashi. I do not speak for him but for myself as I understand the teaching. When Musashi says "when you cut have in mind that you cut and only that", I understand that one has to be simple minded
. There is a power in uniting mind, body and sword. If you do not want to cut, do not wield the sword. Of course, because of our humanity and because we recognise humanity in the other, then if there is an opening to stop the sword before cutting then of course we must do so.
If one picks up the sword without the mind of cutting, one lacks sincerety. That is why there is a teaching that goes "learn the heart, only after learn the sword".
When I hold the bokken, I start holding with the hands, then the arms, the body and sometimes the heart. The symmetry is done by uniting the 2 hands as 1. That implies a lot of work. Just simple work for a simple mind