Putrid Faceplate  

 

First off, if you're heading to this spot to snag the mask, Xorikaan is not a common spawn. I've now camped him for 3 days for 3 hours each day and seen him only twice in those 9 hours. The respawn is around 20 mins or so for the PHers and all other mobs around.

I've killed this guy both times that he's been up and both times he dropped the belt item, NOT the mask. I've also searched the bazaar (on Xegony) for this mask for months and never seen it for sale.

I'd say this is much more uncommon to rare, rather than a common drop.