The wings are separate objects; I used Lock
& Key to "lock" them to unactivated bones within the girl's back.
Making the wings separate objects gave me greater control over the Cel-Look
Edges ink colors used for each object (black for the girl; white for the
wings). I chose Cel-Look Edges over Fast Fresnel
inking (or its Super Cel Shader 2.01 counterpart: Bump Edges) because
I wanted a line of even width.
I used SuperGlow to generate
the single-color edge glow, creating a "halo" effect similar to the ones
used in Escaflowne.