Defeat 10 servants from the East
I was doing quests along the eastern arm on both sides, but not getting anywhere. Not to get all B.B. on you, but turns out, they’re referring to East as in East Asian. So you’re looking for servants like this.
I don’t like following guides; I think they detract from the sponteneousity and fun of the game. But perhaps I should cheat a little sometimes to save confusion.