Tamult

Looking at Edelgard's clothes in particular for this, you can see that at these two timestamps (sorry for doing this very quick and dirty), that class changes (which seem to be by completing an exam) do change the dress somewhat. You are right though, that is a rather weird lower half, looks like some sort of embroidered leggings (definitely a pattern going on in that picture) but still doesn't excuse the inconsistent design. https://youtu.be/8OwUB8gf5Ac?t=264 https://youtu.be/8OwUB8gf5Ac?t=247