Okay, so she's not a witch but a demon. It's canon.
All jokes aside...
1) why Erden's father's statue doesn't have a face? is it because
a) they didn't want anyone to accidentally glimpse it (and then for Erden to accidentally hear he's handsome)
b) he was too handsome for the craftsmen
c) his handsomeness was stolen by a demon
2) what if that person who warned her is a demon, vying for Erden's face next?
...
Why the curse argh, what's the story behind it???