Based on the physical description, she would need to be some kind of fomori or fomori halfbreed. Read my little blurb on them in the intro. The fomori are basically a primordial off shoot of the fae. Monsters like cyclops, minotaur, gorgans (medusa), harpies, and ogres will all be fomori. She can't be a cross breed of the Seelie and Unseelie courts, by the way, because the courts are not faery races, they are organizations to which faeries are sworn. Some faeries like the highborn might be born into one court or another, but it's still not a race. I realize that in some faery mythos the court system is way more integrated with their nature, but in this one it's more cultural.