I just got Reaving Wind the other night. Here's a quint tip for anyone still needing it.
Camp in the Glacier @ I-9 just past the Ruzors (off to the left side as you were going to Fei'yin). I was able to get myself wedged inbetween some rocks during the fight. It helped when the Amp would spam its knockback.
Blu Brd Dnc Pld Bst Rng LVL 90
"If you immediately know the candle light is fire, then the meal was cooked long ago."