You're right Terry, it's not like a being far less powerful than Omega Weiss like Cloud has ever beaten Sephiroth... Oh wait, looks like your logic falls flat on it's face here, doesn't it?
The creators have said nothing surpasses Sephiroth, not that he can never be equaled, and we've been shown a few times in the compilation that more powerful doesn't always mean victory. If Cloud can take down Sephiroth then Omega Weiss' odds aren't bad at all.
Indeed he is. The guy was hailed as the perfect soldier, considered so powerful that thye kept him chained to his throne and sedated most of the time. In addition to this they felt it necessary to give him a special restriction chip that woukd kill him with a virus in three days if the Deepground supercomputer failed to register lifesigns from the Restrictors.
The man is so powerful that he manhandled Bloodburst Rosso and Arch Azul while literally only using on hand. These two in their base forms are as skilled as any elite 1st Class like Zack. When Hojo is controlling him he puts the wood to Vincent with just the power of base Weiss, we know this by the fact that Hojo says he wants to test the body, the game says he is only "Weiss thr Immaculate," and Hojo says his body is one with Omega just a Vincent's is with Chaos(Vincent always has Chaos in him but he's not always using its power).
When you take a being this powerful and then add the power of Omega, the ultimate WEAPON, it becomes one of thr most awesome powers in the VII universe.
It is absurd completely to say it's impossible for Weiss to win. He may not be stronger than Sephiroth but Fascistcrusader has a point to where it didn't say anything wasn't equal.
He does have very strong power, i say he would be a very good match.
The only thing i think is that when they said there was no power stronger than Sephiroth i think they kind of implied that there was no one equal to him. But like i said we can't really know, i mean if someone weaker than Weiss like Cloud beat Sephiroth, whos to say Weiss can't win? I'm only saying it would be unlikely from the point of view i look at it.