[JamOfBoy]

In the grander scale of Bonder, Fight As One is only egregiously strong from the Two Souls Beyond passive that grants it when installing. This sort of makes it hard to look at Fight As One on its own because changes you make to it might serve to make Two Souls Beyond installers stronger, which isn't quite ideal. I think if you ignore Two Souls Beyond, Fight As One is perfectly balanced for one bonded youkai, but horrible for multiple bonded.

I think Fight As One's range should be inversed from your proposal - if you have multiple bonded, the range of Fight As One increases. If you have only one bonded youkai, the range is smaller. Bigger buff, smaller range. Smaller buff, bigger range.