hmm.........
The black wings is hard to understand if you tried to read it half wise. Well I only read the unofficial translation and and very hard to understand if you read it directly.
From what I can gather ( hope someone correct me or give more info )
well I can tell a story about when it first appear ( I haven't read vol 15 yet )
hope someone clarifies more but the end point. WINGS = AWAKEN = AIM