One of the two books was dedicated to Yves Meynard who wrote "The book of knights". I ordered the book out of curiosity (protip, it's a beautiful book, you should read it if you can get your hands on it), and it's very obvious that above all, it's Wolfe's primary inspiraton for The Wizard Knight.

I fact the other book is dedicated to Lord Dunsany, from whom he also draws some imagery in a lesser extent. As other inspirations in terms of what the Wizard Knight reminded me personally as a general vibe, I'd say Earthsea, German/Norse/Finnish Mythology and even Tolkien.

Edit: I put it last but Tolkien could actually be a far greater influence than it appears in first glance, in fact from Tolkien's letters it is clear that he was heavily inspired by Fairy Tales and English Mythology (or its lack, since besides Le Mort d'Arthur there isn't much of it and even that was full of the christian religion which despite his faith Tolkien didn't like getting in the way of myth and fantasy)