Not that I'm trying to string up Sanderson as an exemplar of quality writing, but to be entirely fair, the selection you picked out of Mistborn was written to be a part of a man's private journal and intentionally has a different tone and style than the rest of the book.

As far as examples of good writing in fantasy? I struggle to think of any that meet the standards you've set. Raistlin mentioned Rothfuss, and while it's certainly different (first person narratives are hardly a common structure for fantasy), I wouldn't say it's anything special otherwise. Better than most other fantasy? Sure. But the prose is hardly moving.

Frankly, I don't read fantasy to be stunned by an author's prose. I read fantasy for the stories. I read fantasy for the worlds. I read fantasy for the creativity of everything else and accept at least passable prose to deliver it. If I want to read something where the quality of the prose moves me, I'll pick up The Mezzanine. I think if I started enforcing standards for prose, I'd miss out on a lot of good stories that are more concerned about telling said stories than being a work of art.