Ascians

[Viridiana]

If your starting city-state is Limsa Lominsa you may remember defeating this particular Ascian and his gargoyle minion in a lower level battle at Swiftperch. What’s interesting here is the glyph he displays – it looks as though it may belong to Zodiark himself.

Same guy shows up in Gridania, so most likely shows up in Ul'dah as well. I'd tentatively say you're probably right about black-mask Ascians.