He is a skilled workman.
That politician is known as a shrewd schemer.
策士 explicitly means a strategist or schemer, often in political or military contexts, whereas 仕事師 carries this meaning only as a secondary, contextual nuance.
Compound of 仕事 (work, job) and 師 (master, specialist). The term likely developed from referring to a master of a trade to a more general term for a capable worker or schemer.