Though her abilities aren't really in relation to one another, Toph from Avatar: The Last Airbender is an example of a well written disabled character with powers. Despite her blindness, she's witty, snappy, and crude in the best of ways. Though it also acts as her flaws - she's quite judgmental of "weaklings" a lot and stubborn as a bull - she doesn't let her blindness bring her down, and when she gets into an actual battle, she knows what she's doing enough to be a total powerhouse, but also can be tripped up, creating a balanced fight between her and her opponent.
The "demon spirit inside of a person's soul" cliche. You know, Naruto and the Nine Tails, Ichigo and his Hollow form (before he gets split into even more powers; want to know how to do this cliche as poorly as possible? Read all of Bleach), Eren Jaeger and his titan form, it's been done in different forms - but similar concepts - time and time again, and it's most prevalent in anime/manga (a Western equivalent would be something like the Hulk). Often times they have to learn to control it/come to terms with it, or find a way to get rid of it. Sometimes it's a demon, sometimes it's a curse that manifests itself as an alternate personality, but there are always new ways to do it if you're willing to think outside the box (we do it in Time Gate too).