Complex sentence: Sten's first action is a meeting with "moderate" Talamein, ruled by merchant prince Parral and his prophet Theodomir, and offering them mercenary services and unification of the Cluster.
Split into simpler sentences: Sten's first action is a meeting on "moderate" Talamein ruled by the merchant prince Parral and his prophet Theodomir. Sten offers them mercenary services and unification of the Cluster.