If he was so left handed that he was unable to learn to write properly (right handed) he should have had similar problems learning to use weapons properly (right handed).
Actually I have found being left handed a distinct advantage
with weapons and empty hand.
But if he was ambidextrous, he could have had learned to write with his right hand.
Ambidextrous? Generations of left handed
people were forced to write right handed.(as a product of a catholic school education I was myself, until my mother put an end to it).
Takeda was interesting guy beyond all doubt.
Refused to be called Soke
Refused to be called Menkyo
Never called himself a shihan
His son stated that both he and his father had no rank
Did very unusual martial arts
Handed out an ever growing assortment of makimono (that came from where?)
Taught different things to different groups, instead a fixed set of kata (unlike established koryu)
Then, added ranks and awarded them in an art he said...was not his.
Many ancient densho survive.
We have not found nor ever heard of a single one for this "Daito" ryu from Aizu.
I think that the Japanese had trouble saying look at me I am a genius
(even when they are).Or look what I created!
So instead we hear stories of God handing out scrolls
, Tengu giving whole systems, mountain tengu teaching systems
..and guys being "General affairs director" of an art with oshiki-uchi,
Or sons stating that their dads studied an array of Koryu arts and blended them together to make aikido.
Internet bloggers would have had a field day with some of these guys were they alive today.