Heraldry of the Empire of Lumiaron

TL;DR
Heraldry covers the rules associated with the creation of the Coat of Arms. All coat-of-arms devices must be registered with the Bardic Guild who will ensure that no coat of arms is duplicated by what has gone before.
Only landed noble families are entitled to a coat of arms.

Rules of Sigils

Sigils are the devices on top of the main crest, often seen as crowning a shield. They build in an hierarchical manner in each duchy as follows:

• Highest rank family: The Ducal family would be allowed to use the Ducal Crown as a sigil. Their main device of their coat-of-arms would become the sigil of their counts and the sigil of their Duchy's coat-of-arms. For example: Duke of Etendulat (Family Eten) => trippant deer on shield, ducal crown on top
  
• The counts who swear allegiance to a Duke would take the main device of the duke's coat-of-arms as a sigil for their coat-of-arms. For example, the County family de la Cham in Etendulat => carp fish on the shield, trippant deer on top
  
• The barons who swear allegiance to a Count would take the main device of the count's coat-of-arms as a sigil for their coat-of-arms. For example, the Baron of Somfaux (Family du Mamel) => hunter on the shield, carp fish on top
  

The Duchy of Etendulat gets a coat-of-arms apart from the Ducal family and that would also echo the Ducal sigil as follows => wheat on shield, trippant deer on top.