It already had feather wings at the time of the Devil's 33. But yeah, thanks for those links. Even after he was already named the Storm King, though, notice that the "Winged Beast" still has a skeletal tail. What's up with that? And I also don't understand why the skeletal version of the "shadow" had a guitar in the place of a sword.
They call him the "wind," by the way, both him and Sora. For Ikki, though, Simca once called him a "powerful and tempestuous wind" or something along those lines, and Sora, during their disc battle, said to Rika that he's a wind that has already become a storm. [Though, I think it should be that he powered up from a wind to a storm when his Road became the Hurricane Road.] I think that, because of that, the Storm Regalia needs to be built such that the Wind and Rumble components are given center-stage, while the other Regalia cores' parts are there to augment them. Mainly due to the fact that, yeah, Ikki is the wind that became a storm, or a powerful and tempestuous, stormy like wind, and he's also first and foremost a wind-user.
And remember what I said about the Storm Regalia being a combination of Wind + Rumble at first, due to Kururu deciding that she'd fuse the mechanism of "Wind" with the mechanism of the "Rumble"? The one wheel of the core the way it was before having those other cores combined into it, that we saw when it was damaged, has division-lines on the white edges of the wheels that look similar to the ones on the Bagram wheels, and it also has the same skull with wings. Page of the wheel from back then:
http://www.mangafox.com/manga/air_gear/v30/c286/16.html. The Hurricane Road, at that point, was a combination of Wing Road plus Over Road, and the Regalia was reflecting that. I'm pretty sure the Storm Regalia core does have the Wind Regalia core combined into it. Kururu could have made another replica of it (directed at anyone who would otherwise wonder how she could incorporate the Wind Regalia core into it when Sora already has the one she made).
To show the Wind Regalia core:
http://www.mangafox.com/manga/air_gear/v16/c137/19.html (I need to find the page that has Kururu laying her own version down on the piano, in the "factory," but that'll take some time since I seem to be very far from it right now). The parts where the core is splitting there seem to be close to where the division lines on the Storm Regalia core were when it was just Wind + Rumble, right?
Anyway, I'm still hoping that Ikki will give back all of the Regalia cores that are being combined into his Regalia, besides the Rumble one and maybe the Thunder one. He won't give them back now, I know that; most likely once Agito and Kazu can ride again since right now they're injured (Kazu is a lot more worse off than Agito). If Ikki keeps the cores, that's fine as long as Kazu and Agito get new Flame and Fang cores made for them.
Edit: I finally found it; the image with Kururu's version of the Bagram. Here:
http://www.mangafox.com/manga/air_gear/v16/c135/14.html. We see the division-lines and the wing "feathers" more clearly in this one than the one I posted, no?