While in Lezard Valeth, leave to the world map and head for the Seraphic Gate. Alicia at L60 would be a good idea. Defeat the gate guard and go through 3 scenes to fight Celeste.

Upon beating him you get the wand and as an added bonus, you get Leone and Dylan back. But they are at a very low level. After finishing your task I suggest you leave the the purple shining mirror and save.