Re: Where did O-Sensei get his sword training?
I have to say, with great respect for the research you've done, it's still important to remember we are piecing together bits and pieces from the available evidence and there's more about the lives of both men that we don't know than that we do. It's very different to say "There's no evidence for him studying X" than to say "He never studied X." I know you know that, but the distinction gets lost in discussion.
In a lot of ways I'm more impressed by arguments of the form "Whether he studied X or not, it doesn't seem to have influenced him because there are no aspects of X style that show up in his own style." There, I think, we are on firmer ground.
What's the real story with regard to the Shinkage-ryu menkyo?