Did you miss the part where it was said Bhunivelze ripped Serah's soul from within Lightning and threw it away into the void beyond? Guy's a douche.
It was not him. Lightning made it. It was revealed after the final battle.
Eh no. Lightning is responsibe for Lumina yes, but she didn't intentionally remove serah's soul from her body, that was Bhunivelze. Lumina just happened to find her soul drifting through the chaos. --- No. XI MARLUXIA In the arc of his scythe, flowers grow and all else perishes.