Dragon by Steven Brust
As a human and an Easterner, Vlad Taltos has survived in the decadent city of Drilankha by practicing the trade he knows best - killing people for a living. His skill as an assassin, and the timely intervention of his telepathic winged-lizard companion, Loiosh, have won him a relatively safe post in House Jhereg, running the rackets for a section of the great city. But when a powerful Dragonlord commands him to track down an enchanted weapon of great power - before it has even been stolen - Vlad finds himself inexorably drawn to the last place he wants to be, a total war on an apocalyptic scale between two sorcerous enemies, where he must play crucial role without a clue as to what is expected of him. Only his cunning wit and well-earned distrust of all things magical stand between Vlad and a most unpleasant demise.