I will educate certain people in this thread about the abilities proved in canon that Sephiroth has and what he can do.
Now granted Sephiroth doesn't have many 'feats' however his implied strength, speed etc is HUGE. The following few paragraphs etc will inform you a bit more about his awesome power.
http://forums.thelifestream.net/advent-children/'there-is-nothing-stronger-than-sephiroth-nothing-above-him'-is-this-real/15/
Summary of quote:
In the Japanese audio commentary(sp?) it is stated that "In VII, a stronger enemy than Sephiroth can't be made".
So, here's an update on my search, guys. It's taken a good while, but I finally found a Japanese site with a claim that the staff commentary features a quote to the effect we were looking for:Link
About a quarter from the bottom of the page, there's this:
<Snipped, Japanese characters aren't supported on this forum>
That part in the direct quote brackets basically reads "In VII, a stronger enemy than Sephiroth can't be made," with the staff of AC credited for the quote.
That webpage is basically a summary and review of the movie, with a few quotes from the AC commentary itself sprinkled throughout. I'm assuming this statement about Sephiroth is meant to be a direct quote as well.
In any case, even if it's a paraphrasing put into quotes, this is still an actual Japanese source using <Japanese Characters> (kyouteki) -- specifically meaning "stronger/more formidable enemy" -- rather than just <Japanese Characters> (ijou; "above"😉 as was the case with the other Japanese website linked earlier.
In other words, this gives a specific context to "above" -- strength -- and coming from a Japanese source, concerns about misinterpretation of "above" are certainly diminished.
So, with that discovered, ximaus and I both believe that the Nomura quote exists. The claim that Nomura said there can't be a stronger enemy than Sephiroth in FFVII is apparently true.
If you would like to disprove this go ahead and watch the commentary of both english and japanese version of AC, then come back and say "Oh yeah thats right.".
Okay, so from this we know that there can't be a stronger enemy than Sephiroth in FFVII is true. Therefore: Any strength seen in any enemy in the FF VII world is in fact weaker then Sephiroth, think about it.
http://www.youtube.com/watch?v=L1m79XasUd0
Watch this ^ Sephiroth is stronger then the guy with two swords. Sephiroth in fact moves faster then anything I have ever seen in WoW, Sephiroth would not be hit by anything that Illidan could do, even Polymorph. (and if Polymorph is able to be used, why can't Transform materia be used on Illidan so that he turns into toad?).
Also to the people that say materia takes a super long time to do, in AC Bahumet is summoned with a throw of a hand, Therefore the cast time for Transform would be instant. (Also in the game when someone casts magic 'time' is frozen).
Sephiroth has also shown that he can fly in AC and the original game.
http://www.youtube.com/watch?v=nbwiDIy-m2Y&feature=PlayList&p=5EDE0A7C0F8A7994&playnext=1&index=58
(@ a certain person.) At about 3:50 you can see the building fall, with Sephiroth floating below it. Sephiroth kinda just stays there talking, Sephiroth then looks forward and the bit of the building falls, Sephiroth is not suprised at all...but then again he rarely is. This part of the building was not once touched by Cloud or Sephiroth, so you can come to your own conclusion. However to me it looks as if Sephiroth done it intentionally.
Youtube Video Shows a weaker Sephiroth cutting through tougher materials then what Illidan is made of. (Yes it is a training simulation. But look at the AC vid again.)
How Sephiroth wins:
Before Illidan can even think about doing anything at all, Sephiroth has already sliced him in half. Thanks for playing.
How Sephiroth wins 2:
Sephiroth plays around with Illidan for a while before bending Illidans will so that he is then controlled by Sephiroth.
How Sephiroth wins 3:
Uses a certain materia combination to come back to life and heal to full whenever he dies. (Gameplay)
Random tidbit from FF VII Ultimania (Official Source - unofficially translated):
http://au.faqs.ign.com/articles/698/698416p1.html
It's mentioned that after Sephiroth jumped into the Lifestream back in
Nibelheim, his body dissolved, but because of his powerful will , he reformed it at the Northern Crater, where his life energy and Jenova's head were washed to.