Since Duke of Earl is slang for a person that succeeds on a task, the opposite of a Duke of Earl would be a busta or buster which is slang for a person that fails at a task.
A Duke is the highest level of the peerage. The Royal Dukes, currently are Charles, Prince of Wales, Duke of Cornwall Prince Andrew, Duke of York Prince Philip, Duke of Edinburgh Duke of Kent Duke of...
A duke holds control over a piece of land, kind of like a sector. An Arch- Duke holds control over a larger piece of land, basically a domain, which is usually made up of sectors.