I was reading the Manga again and I decided to see if I could come up with some ideas for what the meaning of the title is. "The Third Power"
Note that these are only ideas.
The Third Power | Rikodou Sennin
We know that the Sage split his powers into 3 ways, the 2 sons which later became the Senju and the Uchiha clans. Then we have the third power he split, namely the Juubi. Oro might have worked on something regarding the Juubi.
The sage might also have split something else up or his power. Maybe he took a little bit of the Uchiha and Senju power and placed them into something, which later Tobi got his hands on, or something else. Or maybe its just sealed away somewhere.
I'll edit if I come up with anymore stupid ideas...
Note that these are only ideas.
The Third Power | Rikodou Sennin
We know that the Sage split his powers into 3 ways, the 2 sons which later became the Senju and the Uchiha clans. Then we have the third power he split, namely the Juubi. Oro might have worked on something regarding the Juubi.
The sage might also have split something else up or his power. Maybe he took a little bit of the Uchiha and Senju power and placed them into something, which later Tobi got his hands on, or something else. Or maybe its just sealed away somewhere.
I'll edit if I come up with anymore stupid ideas...