Supposedly you get a face from Lady of Light and the other from Damsel. Then you get a 2-slot combine item from completing ALL the raid achievements. You combine in that container and get a class specific face item. At least that is the speculation if we're talking about the same thing.
I think the Vanquisher of Light and Decay give eyes which fit in the blind vessel container though. I think the faces combine in some other way.
Surprise surprise Without any type of dev input it's gonna be at least a month-ish(?) until the containers and stuff are available to people. Oh well...
The devs are neck deep in this TLP server, I doubt they are even thinking about the expansion they recently released.