A Sinecure is a "cushy" job that is usually given as a reward. It literally means "without care" and is a job without the cares of actual results. It is typically given for reasons of status, prestige, or patronage.
As an adjective, the word "titular" would be sufficient, implying that the job is one in title only. E.g. The titular Crown Steward and Baliff of the Chiltern Hundreds did such and such.