When I first saw this shot, I thought Disa blended with the rock (partly due to dim lighting*). Then I thought that the draping of her costume resembles rock striations but that's not actually it either.
"With Disa specifically, we talked about her being of water. I did all these other sketches, which are sort of just big bulky sketches because everyone tends to think of Dwarves as these sort of mass blocks. And actually, when you meet Disa, she's so warm, and there's this beautiful, sensual quality and warmth in the lights in her eyes, and all of those things were just about bringing them out more."
"And she talked about herself being the water over stone, which I thought was a beautiful thing, which sort of linked into the singing and that."
Fitting that her dress looks like running water, considering the view outside of Khazad-dum, similar to how elvish costumes uses vines and leaves.
"So we went back to Sophia and went, “Let's use all your beautiful physicality and make her sensual.” We were showing her statues of Brunhilda and all of that Nibelung, and that’s where the leg came in.
Then we went, “Well, how do we still make it feel Dwarfy?” And it's not just noses and ears and things like that. We looked at the boots, we created these boots that felt like Dwarven feet and gold feet, that was part of the craftsmanship of this world."
Disa is dressed to be desirable and to support Sophia Nomvete's performance. It's also not mentioned in the article but it bears reminding that in SDCC 2022 interviews, Sophia confirmed that her costumes were also designed to accommodate her as a new mother.
This isn't really an analysis but more appreciation of what Kate Hawley (who also worked on the Hobbit) brought to ROP. Luca Mosca worked alongside with her and built upon her foundation for s2 but I don't think new costumes were made for Disa. I might have love every costume but not liking an aesthetic doesn't mean there wasn't any thought put into it.
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[*Caps are brightened for visibility!]