I haven't really touched on that, since I've been trying to keep things clear and (mostly) understandable.
Of course, that's the whole paradigm of Kototama, and the chanting that Ueshiba did was used for that purpose. Basically speaking, I think that he was using it to focus his intent in certain ways, and this worked well for him because of his religious beliefs and background.
For other people, perhaps not so much (it never did much for me). Notably, he discouraged people from joining his religion or joining in his religious exercises, so maybe he understood that it was different for his students than it was for him.
How about the Kiai:
"Ya" "Toh" Unn (non-verbalized)" and "Ehii"
They contain A, O, U, E, and I and O-sensei used them martially, not just religiously. They too were passed down in Doka (to all who care) and Kuden (to some at least).
Just as A and O were specific referents, O-sensei used these kiai (my computer insists on "kiwi"
) in specific ways . . . do you see a connection???
Do any Koryu aficionados???
FWIW, (very little no doubt) I learned these in the context of Ken . . . (I learned almost everything that was "a thing"* in the context of Ken from my teacher!) [Back in the "old days" that was the the quintessential answer to any conundrum raised in the dojo, "Get your ken!" I kind of miss the "old days."