Reaper's Eye tells the story of Daryus Gaunt, a former crusader against the demon invasion in the Worldwound, when he meets a talking weasel with an agenda of its own, which draws him into a plot to unearth a long buried secret. Daryus is stalked not only by the weasel's former master, a powerful witch looking to break a deal with a demon, but also by his former crusader allies who now consider him a criminal and fugitive....except all of that really isn't what the book is about. That's how the book is marketed, but in fact, Daryus' employer, the Pathfinder Shiera is actually the larger character and protagonist of the book. It's her story to unearth a lost temple city and discover what was hidden at such great lengths, all the while evading the plots of the witch to manipulate her quest and steal the hidden power once she does all of the hard work.
While the witch has a name, he's not a very memorable villain, despite having many point of view chapters which in no way enhance the book. I'm fine with books with multiple POV characters, and in fact in general love that narrative style, but in this case, having the bad guy's point of view detracts from the book. First, he's not very interesting - he wants power because...he's a bad guy who always wants more power. He's also incredibly dense about his plans being unrealistic. Finally, as a villain who is generally pulling strings from behind the scenes, showing what he's up to actually detracts from the surprise and mystery of what's going on. Hearing about him solely from the point of view of his former familiar would have been far better.
Finally, while the actual plot of discovering a lost temple city is passably entertaining, nothing about it is closely tied to the Pathfinder universe, despite being set there, and nothing about the search itself stands out from other similar adventure stories. Generally I've liked Richard Knaak's works in the past, but this book is a bit of a misstep. I much prefer his original works to this, as well as his older game tie in fiction set in the Dragonlance world.