My hair is magical~ and silky and beautiful Taken are evil of course, trust Eris in all she says

Dregs primarily have bad hair, and vandals (as Aer is a vandal) wear helmets obscuring their hair as such. Female vandals often hide in the military as well, because in a patriarchal society such as the fallen empire, females don't like to be known or show off. Aer is the daughter of a archon now though, so it's entirely possible that the other Eliksni are too scared to challenge her, because of her father. This implies that it's possible that vandals have beautiful hair and it's possible that Aer doesn't have to wear a helmet because of her position.