What does Nathan think?
Different schools of sword often have some way of determining the correct blade length for that style. How you use the sword (specific to your ryu-ha) determines its dimensions. For example, if I was do do Yanagi Ryu style kenjutsu, I would need a much longer tsuka than the Shinto Ryu that I do study. In some styles of Iai, the techniques call for a VERY long blade, but if you were to study Shindo Yoshin ryu, you would want a sword you could hold by your side and not touch the ground with.