Quote Originally Posted by Halenite
Quote Originally Posted by Xurts
Just because he is seen absorbing a blue materia doesn't mean that is the only one he used. I'm sure he had a red one in his arm too, we just didn't see him put it in. What is so outrageous about that? We don't need to see everything that goes on behind the scenes.
Sadly, this is not correct. You see what color of Materia is active at a specific time, as shown with Yazoo and Loz near the end. We see that Kadaj has a blue/green (I thought it was green, some say blue, so whatever) glow on his arm, implying that materia color is being used. Therefore, he is using that color materia to summon Bahamut Sin
The glow on Kadaj's arm was different from Yazoo and Loz's at the end. The materia that Yazoo and Loz had in there arms was actually glowing in their arms, you could the individual materia that they had. But with Kadaj, his arm was letting off some sort of blue-green flame. The same flame can be seen when he is talking to the children at the Forgotten City. And I doubt he is using materia then.

I think that Kadaj's blue-green flames look an awful lot like the Spirit Energy that emits from Cloud when he is using a Limit.