The difference here is that they can get away with using any English name they want and don't even care about the meaning, but using an exotic/foreign name like Nasir is a wholly different story, at least for fantasy fiction like this. They might have wanted to have some hidden meaning in the name if they went that far. I also noticed that most, if not all, dragons have tan skin and live in a relatively dry country.
Dunno, Kevin sounds too...modern and un-knightly to me. Kieran sounds more like a name from the middle ages. Same with Stella and Astrid. Stella sounds like the name of a common person from modern times while Astrid sounds more medieval and noble.