It's clear that you didn't find Seph hard at all in KHI.
But he's much more difficult to PWN, because you basically have to fight him with either a full and upgraded set of armor and accessories, or you have to get loads of Defense Pluses. Unless your reflexes are godly, and even then, Seph has some kind of homing teleport. The Arena's bigger too.
The one that corncracker wrote for the KHII frontsite is very good, though.