Re: Iwama Ryu Bokken
"Training in the aiki ken and jo leads to a increased understanding of combative distance, positioning, and body centering. It develops good posture and strengthens the arms and shoulders which in turn aids in the execution of empty-handed techniques."
- from <http://www.iwama-ryu-tr.org/eng/iwama.html>
"...Many bokken reflect these differences but we also see wooden swords that are not direct imitations of live blades. In fact, bokken are not generally intended to mimic the shape, weight or feel of a steel samurai sword but instead intended to facilitate specific movements."
"The Iwama Bokken of Takemusu Aiki Aikido is 41" long, has a moderate curvature and, with its fairly stout proportions, has a feeling of decisive to heavy balance. The defining feature of this weapon is its solidness and simplicity."
- from <http://www.kingfisherwoodworks.com/>
Based on the above, Saito Sensei seems to have designed the Iwama bokken for the purpose of facilitating good aikido movement. Hence it lacks most of what we would think of as traditional "sword-like" features like tsuba and blood grooves.
Anyone else have other clues?