Re: Weapons training leads to good aikido.
Good post David. I like your expression "human-to-human interaction" --- Sugano sensei teachs such things regulary. This is very high level of practice.
But for me, weapons practice have two important reasons:
1. develops "sword spirit" or weapons spirit.
2. teachs skills normally learned only in competition environement.
There is always very big difference between two aikidoka with comparative level of technical skills, if one practice regulary weapons and other not at all. I know such case personally and it is simply matter of different state of mind.