Not ALL demons use those,it's more of a light-armor for succubi and inccubi.

But the general concept is there : no plates and insignias and all that fancy stuff.
Demons use more anatomically fit armors that can augment their endurance and strength...with more focus on endurance,since they are already pretty strong on their own.
Why do they need endurance?Angels are purely ethereal in their normal/battle form [that is,when they dont solidify themselves to look human/pretty/not-so-blindingly],demons are as physical as mortals,although they are tough...really tough...must i say,tough as hell.

Although they prefer utility over aesthetics,they can turn their wings into capes or cloaks.

Pretty much inspired by Crysis's power armors,Metal Gear cyborgs and all those hours i spent studying bodies and muscles.


Also...dark hair,hyperdilated left pupil,cigar in her mouth...does she looks familiar? :3