Spoiler ShowAfter finally defeating Xion i can add 2 tips for the fight, i haven’t seen here yet:
1. When she throws her keyblade(?), block it. After every 3rd time you can teleport behind her and attack. But be careful towards the end of the fight her keyblade creates light beams.
2. During her „normal“ armor phase: At the beginning and the end she jumps around and creates lightbeams, block her. This gives you the Opportunity to attack again, destroy the armor and do further damage to her(IF you block her both times).