User blog comment:Waters Knight/Weiss killed 'herself' in the White Trailer/@comment-9090085-20131219002528

You know, when Aura was first introduced, many people wondered why Weiss didn't heal her scar with it. The obvious answer to me was that whatever injured her had a massive emotional impact - it scared her soul. Thus, her emotional "scar" prevented her from healing her physical "scar".

But if she scared herself... "killed" a part of herself... then it's entirely possible that the physical scar is a manifestation of the "scar" left from the part of her she severed from herself. A scared soul resulting in a scared body.