Historically, a coat of arms was given to one for recognition of service. A monarch or lord would approve them for subjects who had distinguished themselves either by long service or for doing one spectacluar deed.
Two good examples are my family and my husband's family. My family was originally people who were in charge of the management and defense of trade routes. For extraordinary service they won the right to use a name that translates into "The king's own" and were granted a coat of arms that others might know that they had earned the respect of the monarch.
My husband's family were the king's personal bodyguard and were responsible for the daily running of his personal household. Thus their name became the keyholder and they were granted a coat of arms that symbolizes the trust the king placed in them to hold the keys to his treasury, his armory and his personal chambers.

In England The Royal College is still responsible for the creation, recording and granting of coats of arms based on lineage. Coats of Arms can be purchased from the monarch for a fee but, it also a requirement that the person on entity display some quality that would deserve royal favor. Persons or companys can be granted a coat of arms for extraordinary service or distinguishmet (ie a Patent of Arms).

I think this is a great idea for DR.