Knights of Avalonia
Avalonia is a group of planets on the edge of the middle sector, that have a feudal society- the land is worked by peasants who are loyal to their local knight, who serves the current king or queen. But the cores of these planets are hollow, filled with giant automated factories built millenia ago, that supply these worlds with advanced technology for both peace and war.
Armies from the honoured realm are built around knights- extremely skilled nobles who go into battle wearing advanced armour, and wielding extremely powerful weapons. They are supported by loyal warrior servants and other support personnel.
Read more about the Knights of Avalonia, and their rules here: