I can't imagine why you'd be sorry for trying? I was trying to offer a hint with 'who said anything about within'; sorry if it came across otherwise.
Not Dor Daedaloth. If you're willing to make another offer, think about what sort of blackness Maeglin surrounded himself with later in his life - and think about why I would specify that this word didn't refer to something on his face.
hS
PS:
No, it's not hair, but very cunning.