One of the things that made me fall in love with the World of Greyhawk folio were the coats of arms which were emblasoned upon the cover. For some reason, these little escutcheons brought a feeling of dignity and legitimacy to these imaginary lands. It was only as I got older that I realized what considerable liberties had been taken with rules of European heraldry to produce those arms. Now I am not saying that every fantasy world needs to adhere to the same rules that existed historically, however, I think it is important that any game master, world designer, artist, or player making arms for themself think about the art of armory for a moment before launching into the creation of a coat of arms. While you might completely rewrite the rules of armory for your world, or (as I would suggest) have different requirements for each ethnic group or nation, it is good to think about why the rules that existed in Europe existed and to then break those rules with purpose instead of ignorance.