Revelations from Second Coil of Bahamut

[Catapult]

It might be more accurate to assert that Bahamut took the tempered soul of van Darnus and placed it in an aetherial recreation of van Darnus' body, created in the image on van Darnus' soul.

As for Lou, it's not clear if he actually died. During the fade-to-white, is it possible that was a tempering-attack rather than a killer? "You almost managed to seal me. That does it - you're mine!"
(Could Bahamut have rebound himself to bide the time in suspended animation to attain new followers using Lou's skills and knowledge?)
Or maybe it killed him as well and he just made Lou an aetherial body straight off the bat. I'm speculating again. Either way, we've got a problem on our hands.