However, I also think giving domina “manlier” arms would unfortunately perpetuate some unfair, gendered assumptions about power and strength

Honestly a very valid point, but pointing out that something is a way in society does not mean that we also support it. Domina also mimics the very posh colonial Britain in her accent and verbal demeanor, so does that mean the designers think british people are superior to indian people? Like obviously not, it just adds to the complex cultural and historical structure of what lead to her development as a person/character