Re: Iwama bokken vs. "the other" bokken
In the sixtys Iwama, we used that second bokken.That picture is modern, so that's very different.Saito would carry a bunch of them around in a bag.
As far as the first one, all I can say is that some katana schools, including Aikido, people have told me that the actual length of ones katana should be the length that exactly clears the scabbard as you draw. This was from the only caucasion ninth dan in any major japanese art, Werner, who wrote, 'Kendo', and other books. (also happens to be a phd in english) He was 6'4", so his katana, and bokken was very long.
I also knew a 6'7", pure japanese, an 8th dan in Iaido, he could cut a (dead) japanese horse in two with one stroke. His Katana was super long.