Glad I could be of help pointing that out about the arms.
Some thoughts. You said you are somewhat troubled by them looking vaguely high elf, namely the ones that are suppose to be bloodletters as they don't look strong enough. One thing to consider is trying to get the shoulder pads from the 40k Kroot box. They are not overly big and should easily fit on your models and not get in the way of the wings to much. I tried them on some high elves when I was trying to make my own swordmasters so I know they fit.
Not the best picture I have of them but it shows the three first ones I worked on.
Another idea is to extend the hilt's handle further, so that the blade looks like it might be a one and half hander or a two hander. If you look at Bloodletters they actually don't look that strong, part of it is just how big their swords look.
As for coloring, I would perhaps have the main two colors be Red and White with gold or bronze trimming. I can understand not going the black route, but at least with the red and white tone you get a more warlike feel, that these are not the sort you try to appease with sweet words.
One thought on the flamers, I would try and use High Elf bows rather than ones from the Empire. They look fancier and would look better with golden coloring. Might want to even consider giving them burning eyes or something to further them from the other models or larger fires on their arrows to make it stand out more.
And while you said you already had your idea for your greater daemon at least take a look at this model. I am not 100% certain on the size of it but I am sure you could look at Cool Mini or not or similar sites to try and find a picture of one next to something else for scale.
Overall I think you are progressing nicely.