Prince of Spires
Istar
Another reason why it might matter is if they have trademarked the term. I don't think they have in this instance, but in general you probably want to stay away from trademarked terms (within the realm of the trademark), unless you absolutely know what you're doing. Not knowing something exists is generally not an excuse in such a case. You don't want to get a letter from a big corporation that you're infringing on their trademark, combined with a demand to cease and desist and to pay whatever damages they percieve.I don't know anything about Warhammer 40k, so I'm not sure why it would matter. Is Xenos used as a slur or something in that?