The Vertex Tribal mask question

Question 1. The skill gem no stat requirements seems to be bugged or I'm not understanding it as I can't equip any skill gem I please with this helm.
Every skill gem seam to still have stat requirements prohibiting me from equipping them even if I have the right weapon equipped.

Question 2. How does one acquire the no equipment requirement?
I've asked around trade and nobody replies so I'm assuming nobody knows.
Is this a corruption modifier? Is it just extremely rare to get or is there some modification like another piece of equipment required to get that to work?