How on earth does Seven play the fiddle with only one arm?
It's possible, assuming her hair was kept stiff enough that it would hold still. Without having fingers to press down on the strings, however, her range of notes would be much more limited (unless, of course, each of her hairs played different notes at different pitches and in different keys).
Thank you, but Seven isn't the woman with bowstrings for hair and fiddle bows for her fingers, that's Agrafena. Seven is the boy who had his left arm amputated at the shoulder, yet somehow still learned how to play the fiddle. There are a few problems I can see with that.
If Sorrow is the daughter of stars, how come being touched by a star burns her?
Even if she's the daughter of a Star, she probably doesn't have much, or any, light at all considering how much the light of the Stars has faded by the time she came around. The light's probably what's burning her.