Use of Weapons is the third novel in the Culture series by Iain M. Banks. I'm grateful there are so many of these books. I am so enjoying getting to know them.
from the back of the book:
Cheradenine Zakalwe is an agent of Special Circumstances, the elite weapon of the Culture's policy of moral espionage. Zazkalwe has meddled in the destinies of countries, races, entire planets - with everything from military action to plain old dirty tricks.
Finally he's been thrust into the fray on the losing side one too many times, and he chooses early retirement. Yet when Special Circumstances suddenly decides that they want him back, they never anticipate that regaining the burned-out agent will all rest on the power to manipulate his one fatal flaw.
Steven Wu calls it "a compulsively readable book, and a great deal of fun." SFF.net has a review describing it as "probably the consensus choice among Banks' readers as his best SF novel."
The picture at the top of the post is from Amazon.com.