User blog comment:ChishioKunrin/Q&A questions for the December 19th livestream/@comment-26463535-20151215002151/@comment-26397825-20151215003502

Phantom allows one obvious and one minor trait in his RP, which is not Canon; he very specifically made it AU so he could play with it. And that was simply because some Faunus get things like Nightvision, which is technically a secondary trait, along with their obvious trait of things like tails and ears.

Actually, all Faunus may get nightvision, since Sun didn't seem to have a problem seeing when Blake shot out the lights at the White Fang meeting, despite being a Monkey Faunus.

Phantom however doesn't allow two obvious traits, like claws + ears, or tail + ears, and there has not been a single Faunus in the show who does. Otherwise, I'm sure they would have given the Cat Faunus' ears + tails, or any other myriad of combinations.