Social skills are something you learn. Amu gained a few instant skill-ups on exaltation, but thinking back on it, that was in the middle of combat and social skills simply weren't something she cared about at the time.
Failing that, she's ten years old. I have yet to meet the ten-year-old I can't run circles around socially, and I don't believe I ever will.
That essentially just leaves her raw charisma and good looks, which aren't...
bad, exactly. Her exalted status means she doesn't take penalties to use untrained skills, so she's already capable of punching well above her age-group.