While these are good resources, I think it would still be interesting to have a more rigorously reseached historical biography of his life. What Davey describes begs for more investigation especially since in many ways if you believe what is written, there is a much more to find admirable in the life he lived than what we glean from Stanley Pranin's investigations of how Ueshiba lived his.
Certainly someone who is represented by this sort of portrait transformation of outlook, "During the Russo-Japanese War, he used his sword in battle and earned the rather dubious nickname "Man-Cutting Tempu." Yet after returning from India, he stressed love and protection for all creations, and during W.W.II saved the life of a downed American pilot, whom Japanese villagers were beating.", is worth more than a single insiders bio.
The various influences and how that evolved into what he was teaching Teaching Tohei and aikidoka in post-war Japan hasn't been really touched at all. Though he was ten years older the Ueshiba, he died just a few months shy of when Ueshiba passed away.