A more thorough explanation:

Serjeanty is a type of feudal lay tenure that requires some form of personal service to the king. The service required is not necessarily military and can range from small symbolic gestures to significant contributions to the country's defense.

Grand serjeanty is a type of serjeanty that requires the tenant to perform a service relating to the country's defense. This service can be significant, such as fielding an army, or small, such as providing a fully equipped knight. Sometimes the service is ceremonial or honorary, such as carrying the king's banner or serving as an officer at the coronation.

Petit serjeanty is a type of serjeanty that requires only a minor service of small value, usually with military symbolism. An example of this is presenting an arrow or an unstrung bow to the king.

Household officers of the Crown, even those as humble as bakers and cooks, held lands in serjeanty. This illustrates that the required service was not necessarily military and could be any form of personal service to the king. The examples of grand and petit serjeanty show that the required service could range from significant contributions to the country's defense to small symbolic gestures.