Hm, that's interesting! I know dictionaries can differ a fair bit but all the ones I can find have 影 as "shadow". Tangorin lists moonlight or starlight as one possible meaning, but "shadow" is still the primary one. Jisho has it mean moonlight as a compound with 月. My dictionary lists "shadow" as the first definition of "kage" with that kanji as well. Plus it makes thematic sense with her "thou art shadow, I am light" line - "thou art moonlight, I am light" doesn't really have the same effect. I think I'd probably stick with shadow.
Anyway, Chapter 57!
Chapter 58 is coming next Thursday!