I think the write up is fantastic, though the only thing I don't agree with much is the clothing. That's mainly because despite desert heat, you WANT to cover up your body. There's the sand to think about. It's blowing everywhere- in your eyes, in your face, against your skin. Not only is it hygienic to cover yourself up, but it's also protective, especially when a storm hits. There's also the sun to think about. If you're too exposed to it, you could get sun sickness and dehydrate faster (I think?) , so that's why when people are out in the desert, they do wear light clothes, but they cover their whole selves up. It's practical that way. Plus, if the Essyrini are ritualistic, their style would most likely reflect that, too.
There's that, but the new style stuff sort of resembles the island clothing a bit too much, at least to me. Maybe you could do a middle ground?