Darkness Devours question

Face shifting, turning into pure energy (undetectable mist), visions of the future, heightened strength/senses/healing, walking the grey fields, astral travel, some power over souls (like when she yanked Riley out of the grey fields), and turning partially into mist too, like when she uses just her hand to sink into someone's chest. There's more coming, but at this point that's it. She's only telepathic with Azriel, and that's mainly because he bridges their minds together, not her.

Why does she have wings on the covers of books three and four? Did I miss something or is that just because this is the dark angels series?