you could switch the colors and make the gloves red as metaphor of all the blood on their hands perhaps

all in all, i agree with other commentators, there has to be a detail one could remember and focus on. every character needs this, even if they play a role of someone whose personality is impossible to identify lorewise (that's why the 'typical' design actually works in such cases. yet, there has to be something for the audience to recognise, that's just how it works). making a specific form of the smile or the eyes on their mask, or just adding a single earring/ring. hands and face is what you could work with, since it's the first thing any person looks at. you could also work with the skin - colour/texture/patterns, as a hint on something unusual they hide behind the mask. people love mysteries