DH

There are many suspect things about his weapons. But you need to have perspective about certain things. Do you know how many guys broke their promises and or simply the rules and taught koryu to friends. How many others informally traded info ala " You teach me yours, I'll teach you mine but shut up about it?" Oh, the stories!!. It is happening right now in Japan as we speak.
What we do know, (and who knows if it is all); He had a smattering of informal koryu and watching Koryu taught to others. While Takeda taught him, Takeda's own lineage is weird by Japanese standards.
As far as an expert swordsman (wasn't that a kendo and Iai guy?) thinking he was the best in Japan...well, everyone has an opinion right?

Look Takeda and Ueshiba were great Martial artists, so was Musashi-who lacking any formal education in weapons destroyed schools and more or less fought over sixty duels. No one says your stuff has to come from somewhere established to be great stuff. All koryu was gendai at one point and mostly it was from MMA.
Many said Takeda and Ueshiba were genius with the sword. They also both used it supposedly single handed, switching back and forth. Leave it at that. I attribute their skills to their IP/Aiki (gee no surprise there). That doesn't mean that the aiki-ken you are seeing today is what he was doing.
As two Yagyu and Katori guys reluctantly said to Stan on AJ after they visited and trained at Iwama...(paraphrasing as I know the guys in question)
AJ:So what did you think?
Koryu guys: Well. it was interesting.
AJ:So was it good?
Koryu guys:Er...well, we could see how they used it for their aikido
AJ:Come on, what did you think about it as a weapons system?
Koryu guys: Weapons? That aint weapons!
Koryu is Koryu. Aiki weapons are aiki weapons and never the two shall meet, but everyone is happy with what they do.
Dan