I mean, if your point is that the banner-wings don't fit the aesthetics of Shurima, you might want to consider that, from what we've seen, the Darkin themselves don't actually fit the aesthetic either.
Between the few images we have (sheer, fluted metal plates, sleek figures, and divine proportions), and the descriptions we have of some of the other Darkin (namely Naganeka), it could be assumed that the Darkin, true to their names, developed much more feral aspects than their once noble forms.
Pronounced golds with fine, geometric patterns, crests of circular plates or gems, clothes and accents in cool blues, teals, or greens, and the powerful forms of the Ascended, each some blend of human and animal - those define the aesthetic of Shurima. Of course, a few Champions break this aesthetic (Taliyah, Amumu, Nasus, Xerath), but by and large, that gold, Egyptian-esque thematic is Shurima.
And the Darkin...Don't fit that aesthetic, period. The images we have of them are either the semi-human forms of Varus, Rhaast, and Aatrox - who, the former has corrupted with growths on his legs and arms, and the latter two have masked and dehumanized with the iron-like protrusions and armors of their former bodies...
Or of the terrifying, demonic visages of the Darkin in the Great Darkin War page on the Universe site. Steel in terrifyingly simple designs, looking as much like a cage as it does armor. A tall warrior, clad in fluted plate, who looks as violent as he does noble. A gaunt figure, pale, tall, a six-armed heirophant, inhuman and yet all so similar.
Powerful horns curved low, a body made almost of marble, devoid of mouth, but still colossal, borne on great wings of like make.
The Darkin seem as far detached from their Shuriman roots as one could get, so, trying to argue that banner-wings don't belong on Darkin because it doesn't fit the Shuriman aesthetic...It's like saying Pyke shouldn't have Bilgewater attire since he's a Freljordian. He may be a Freljordian by blood, but he's visibly more a Bilgewater Champion.
