Re: "Hidden in Plain Sight" - Takeda Sokaku
The staff taught O Sensei Aikido. It's interesting to watch the 1935 film and see a hint of resistance in his technique before he realized the art. His receptivity was better afterwards. Since there's no video between the Asahi News footage and the 1950's that I'm aware of, I would assume he discovered the staff around 1940 when he was almost 60 years old at the same time he freed himself from all the martial techniques of the past. I'm sure he figured out the pragmatic martial subset of Aiki is actually quite limited and easy compared to training within the entire superset of the preformal field.
For O Sensei the staff became an instrument to work directly with the stream of creation. It was much more powerful than a mere weapon.