In medieval times, when a man was training to be a knight, a varlet, or special servant, would assist him. In paintings of young knights, there is often a trusty varlet at his side.
If you heard someone say, "Varlet! Bring me my hauberk!" you could be sure you'd either traveled back in time to the Middle Ages or were at a Renaissance Fair. A varlet was similar to a squire, a servant and sidekick who could be relied on for help when a knight was just starting out. Later, varlet came to have the additional meaning of "rascal or rogue," possibly influenced by Shakespeare, who frequently used it as an insult.