Hey!
I apologize in advance for the copy pasta, but I wanted to make sure context behind this change was spread around a bit.
TL;DR after our discussion: We're going to roll with keeping her dress as-is
Basically, this is what we would have made Pentakill Sona look like if we had designed her based on the standards we have today.
When we were working on her, we decided a blue tint was better because this is a semi reflective fabric, whether it's velvet, satin, or taffeta, the black would be reflecting color off. Also, the dark, dark blue separates everything and makes her an easier read in game; her etwahl and chains don't blend into her model and muddy things up from game height.
I realize this isn't the answer everyone is going to be hoping for, but I did want to provide some context, as having things change without any kind of reasoning (especially when it's something you like) sucks.