Well Sam, your inquiries regarding kenjutsu bring me up to write a thing or two regarding this ancient art of sword fighting. Please bare in mind this is what I think. In any martial art human takes years to perfect the skills. The art of swift movement is key to success. Practice walking kenjutsu style follow by the way to swing the sword. In kenjutsu we seldom block the opponent sword but we normally deflect the blade away. Destroy your sword and your life will be over.
Sparing using the bokken is quite dangerous especially when we are using full speed and force. I would recommend trying 'Chanbara' do a search in the web regarding chanbara it will greatly help to refine your martial ability. What we lack (power) we can replace by using speed.