The Warlock in Spite of Himself - Christopher Stasheff - Bog

SCIENCE AND SORCERY DO NOT MIX-EXCEPT ON GRAMARYE
Skeptical, cynical Rod Gallowglass is a spacefaring man of science who does not believe in magic. He's also an operative of the agency SCENT, tasked with finding lost colony planets, then guiding them toward democracy and eventual membership in the galactic community.
But when he stumbles across the strange new planet Gramarye, he's shocked to discover a medieval society full of witches and warlocks, elves and monsters. How is it even possible? Worse, Rod's advanced technology quickly gets him labeled a warlock, despite his constant denials.
Moreover, the Kingdom is in political turmoil, with a young girl-queen on the brink of civil war with her rebellious lords. Rod slowly discovers off-world organizations are behind the unrest, trying to subtly corrupt Gramarye away from democratic rule. His mission is threatened at every turn by fascists, anarchists, and double-dealing royalists playing vicious political power games for the future of the most unique-and perhaps most important-planet in the galaxy.
Aided only by a coven of teenage witches, a ragtag army of beggars, and his epileptic robot horse Fess, Rod decides the only way to thwart these destructive influences-both native and off-planet-is for him to become a part of the local fabric and lead Gramarye as one of their own. But to do so, Rod Gallowglass must put aside his own convictions and beliefs, and become a warlock, in spite of himself.