Even the things that for me keep it from being five stars really fall into the category of personal preference. For one, I hate battle scenes. (They are Just. So. BORING. If all books with multi-page/multi-chapter battle scenes could just replace them with a single page that reads "They fight," & then list any relevant plot points, that'd be super sweet.) And then there were a couple of rather mushy scenes that kind of made me go, "Ugh, this...", although I suppose they were inevitable in terms of the story and were admittedly skillfully written.
So yeah. My bar for fantasy is high. The Black Prism exceeded it, and The Blinding Knife was even better. I'm glad I didn't hear about these books until the last one in the trilogy (The Broken Eye) came out, because I can't wait to find out how it ends.
(Update: Eff. I just found out there's a fourth book that isn't out yet. *Shakes fist at sky* On the other hand, this does mean that I likely get another 600+ pages of awesome from Weeks, so on the balance I probably come out ahead in this one.)