Thanks for the emphatic answer.
I was thinking that a family mon was a matter of Honor, and hoping that Takeda was restricted. Wasn't really betting on it.
I did know about the assembly angle on the fittings; but thought that #1 was odd, considering they had been issuing shin guntos for years already.
Still, the "no chance" determination might be a bit harsh. No doubt the Prince had many swords. A shin gunto is part of the uniform; so maybe he had one or more. And why not have one from a multi- Gold Medal winner at the time? (Yes, I'm reaching.)
There's an excellent book called "Gold Warriors" by Sterling Seagrave, which I highly recommend, that describes a sword belonging to the Prince. It was given to him by Emperor Meiji, and did not sound like a shin gunto. The Prince reportedly gave this valuable sword to a young Filipino man he had befriended in the Philippines, along with a tunic (not uniform). The sword was later destroyed by being used to cut sugar cane. After the war, Prince Takeda became a "compliance officer" where he could have set the example and given up a sword or two. (Okay, now I'm really reaching.) But can you really say "No chance"?