Originally Posted by
Halenite
Just because it wasn't in the game doesn't necessarily mean it's new. I mean, there's no possible way the team could've gotten every single materia in the world is there? We do know, however, that it is unlikely that the box Loz took from the church (the one with the materia) contained the Bahamut Sin. Unfortunately, we do not know where Kadaj got it from. We also know (more than likely, this is true anyway), from the debate between me and Xurtz, that Bahamut Sin WAS, however summoned using a blue or green materia (I again, I say either/or because I think it's green, others think it's blue) meaning it isn't necessarily a summon Materia.
I do have another theory, however. We do know the SHM are remnants of Sephiroth. We truly don't know what these three are truly capable of. It's possible that Kadaj may have CREATED the Bahamut Sin.
Any thoughts?