Dresses? Well, creations that can be worn on naked skin.
Erotic Armour
You could also call them "erotic armours". That would have a martial conotation. That is the reason for the lady on this pic holding a sword.
Best would be to call them "steel lingerie".
Fantasy Fashion from polished steel
In the year 1983 the book "Sexy Robot" with paintings by Hajime
Sorayama was published. Shining female robots are to be seen there. That was the initial inspiration, thanks a lot, Hajime!
An outfit made from steel does not make anybody a robot. But the combination of skin and steel is the leading motiv!