This can be difficult to discuss adequately in an Internet forum. In those drawings, you are assuming the man on the left attacks, and the man on the right defends? If so, I think I see your point. The wrist position of Right can defend off the edge from that position. To try and deflect off the side would require additional twisting of the wrist, which would become awkward. Is that what you are saying? If we turn this around and make Right the attacker, his stance would change and he would extend forward more, but would attack with a rising cut, Left could defend with a downward motion that glances the two blades along their sides, avoiding the edge-on-edge impact. That would require no contortions in the wrist or grip. The defending motion would be very nearly identical to a downward cut, just slightly angled to deflect the side of the attackers blade off the side of defenders blade as the two blades sweep past each other. I think my position would be that some circumstances make avoiding the edge-on-edge impact easy and natural, while others do not. When In battle, don’t worry about preserving the edge. But I would not say that either way is absolute. Like most things in life, it depends.