Damn, she looks classy.
I get a very Asian theme from her design. What references inspired this look?
There was actually an Asian thing amongst the references, but it's not on her dress.
Carmilla's clothing is a masquerade ball's dress. On Umbra, this is her "theme", down to the battle with her, which has her dance as if she were in a ball herself. Remember those Ghost Dancers from Aria, Dawn and Portrait? More or less like that.
Her complexion is the Asian-ish part -- her skin tone is based on Hindu people. She is not Hindu, before anyone throws a fit lol. Her complexion is not white, and we used the tone of Hindu people's skin color as reference to approach her more ("more" not "completelly") to her Rondo of Blood sprite:
We wanted to not only pay homage to her last canonical appearance on the timeline, but also have a vampiress who is not the "staple pale vampire seductress" type, which is done to death and was done on Judgment to an absurd conclusion. Here, Carmilla worships Dracula as a god, but she ain't no Succubus and isn't trying to become fetish fuel. Her game is not seduction*.
This overt sexual/fetish concepts Castlevania (over)does with evil women are a reason why I choose her face to be concealed, too. Besides her mask being a big thing on the Castlevania lore (something that Judgment utterly ignored), she wouldn't let any human look at her purely out of vanity. So, it's not like there is a hideous visage under there or anything: She's beautiful. But it's her choice to wear this mask as a demonstration of her spiteful, vain nature. Think Vega, but a LOT less stereotypical -- same motivation, different execution.
So, the covering of her face, the ball gown and skin tone were choices made to set her apart from all other vampire-like woman enemies Castlevania has shown previously in recent times, with their cute faces and fanservicy sexual nature. Even Lords of Shadow did this. The point is to give Carmilla a proper presentation and try to restore her dignity, even if non-oficially. Carmilla IS still inhumanly beautiful, but this ISN'T the point of her character here (hence the mask). She's here to make you angry and afraid, and not give you a boner.
*="But Twist, what about
Carmilla? That was pretty sexual. It's part of her character to display sexuality. Remember Laura?"
Laura is here. It's true that the Laura/Carmilla relationship doesn't work properly without the sexuality factor. This is how LeFanu envisioned her. But Castlevania missed the point of the novel, and made Carmilla into a dominatrix, and that's not how it works. It's not a matter of removing ALL sexuality, but instead of treating it with respect and making it subtle. Carmilla's intro in itself (which I cannot reveal now) is how I devised to do this. The ball gown, the mystery of the mask, her exotic complexion for an European woman, every of these aspects are working towards a goal, but all of them are also working to treat this aspect of her character with respect.
In all, it's there, but it's not the focus of her character like it was with three recent iterations of her on official Castlevania games. She must be beautiful, different and well-written before anything. Any signs of sexuality here are here to serve her character, and not to steal the focus.
Sorry for the enormous response
EDIT: Reworded this post a bit. Previously it was a bit misleading what I wanted to express.