Also in one of Shioda Sensei's books is a story of O'Sensei telling how he found from practical experience that the sword is not a practical weapon when dealing with multiple opponents. Apparently he found that his sword became too caked with blood and innards to be of much use for too long. It also seemed to get stuck in an opponent's body.
Professor Stevens wrote in the first book that O'Sensei had never killed anyone, but that was amended in the latest one. Grim, but I think it helps us understand all that Morihei Ueshiba went through to create Aikido.
p.s. Thanks Peter.