Honestly at this point I think the KH look in WoFF was completely intentional just for this exact reason now.
Strike Raid perhaps? Hm. Sora doesn't exactly have a signature move, now that I think about it. He's got plenty of cool moves, but they are used by other characters in the franchise.
Riku, Aqua, Terra, Ven, Roxas, and even Xion have signature moves all their own, but Sora doesn't.
New might be best, yeah. A combination of multiple attacks could work out well to become one new move. Like starts as a Strike Raid, then moves into Sonic Blade, into Ars Arcanum, into Ragnarok with a lot of light.