Have you ever put on Bogu and tried to disarm a semi-skilled Kendoka really trying to hit you? You should try it sometime if you get the opportunity, it puts the "bokken disarm" concept in a whole new light.
I've never actually done this, but I had an instructor once who was big on sword work. He studied Kendo (I believe it was Kendo, might have been something else) as well as Aikido.
He said a lot of things that stick in my mind years later, but one which I think applies:
"If you are facing a person with a sword, get used to the idea that you are going to get cut. If you can live with that, you have a chance of surviving. If getting cut is a problem for you, you're going to die."
That's probably not exactly
how he said it, but it's pretty close, I think. And he said this many times. Sometimes it was a knife, rather than a sword.
I've thought about this a lot over the years when practicing weapons defenses. I'm by no means an expert in this area, but I believe he has a point.