The databook doesn't mean anything. It was stated that they finally completed the technique. The thing that they probably meant in the databook that he hasn't completed it, which translates into that he didn't really complete the technique as it has fatal drawbacks, which was solved by Sage Mode.The one that killed 2 of Kakuzu's hearts was an incomplete Rasenshuriken at 50% of its capacity. A complete
Rasenshuriken has twice the destructive capacity and in HM that is increased even more from senjutsu chakra.
A completed Rasenshuriken should be 2x stronger than the one he used against Kakuzu.
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