I wonder....
Could Silver Crow's wings be a result of IS? It does shimmer in the anime when activated, and Raker has hinted that the wings were a direct result of his desire.
That might explain why his ability was 'hidden': it was never there from the start. It does seem strange after all, considering how other avatars had their full abilities listed right from the start and Crow only unlocked 'Aviation' after getting his wings to sprout.
Though it'll probably take tremendous willpower for you to craft a physical body part out of simply pure thought.
Or could it be that the wings were always there, just waiting to be unlocked with a level-up bonus and Haru simply forced it to sprout prematurely through IS?
That would open up a whole can of worms though.
