Final Fantasy XIV Database - Ffxivpro.com

Firstly, don't panic. That's the reason I'm 1/5 on him.
Secondly be sure to skillchain him as much as possible, the extra damage from it is vital. This means doing Yuki > Gekko (Fragmentation) > Gekko (Distortion). Keep in mind he will 2 hour immediately as you do the same thing, and he has a tendency to use Shoulder Tackle which will stun you and make his own skillchain which can potentially screw up your own skillchain timers. So be sure to seigan third eye before you 2hr to absorb at least one of his WSes.

Other than that it's pretty straight forward, bring a few hi-pots in case you get dangerously low on HP, bring a good attack food to finish him off as quickly as you can and go from there. Good luck~