If after everything that has been said already you still have problems with that last fight and you care about the story, just remember that Lahabrea was inside Thancred and he was probably resisting and giving the first one troubles to release his full power while fighting with you. He's your friend (or your family, as Minfilia says), after all, specially if you come from Ul'dah. Also, if I remember well, we weren't the ones who ended that fight, but Hydaelyn (through us, in that 1vs1 attack), so it could even be that Lahabrea was just playing with us up to that point.
Also, next time put the spoiler tag in the title please, it's easier for people to avoid the thread.
