One thing you'll notice is that each COA has something to do with the area.
Griffindale: Not actually a griffin. however, the People of Griffindale are direct descendants of the Frostlanders, and the Frostlander word for the Eagle (called the Imperial Eagle by Pale- and Estatesmen) is Grifen. Sometime after its conquest, the area itself went from Grifendall to Griffindale.
Artania: The Wall of Artania is a magnificent structure that stretches from North Artania all the way to the coast. the Lion comes from an ancient belief that the sun was a Lion that prowled the skies.
North Artania: The area has often been called the Wine Kingdom. The dukes endorsed this, and the ducal crown remains above the glass, a symbol of prosperity. Some say it also stands for the Great Tower at Firetower, which rather obviously, is a lighthouse.
Xerian (pronounced Chierian) Pale: The most recent addition to the Empire, hence the Pale, the shield shows two centaurs combatant, where one (the grey one) represents the empire (with the red crest). the brown represents the Xerian States, who (mostly) happen to use brass armor. the Grey is the more refined Imperial Steel
North Bloodfangs: Obviously a bit of a copy of the Bloodfangs Ducal Crest. the bird is a crow, in the sense that it's not like our crows. Instead, it acts more like a bat.
Bloodfangs: The main mountain range being. so called for the treacherous paths. the grey-white represents both a mountain as well as a fang (hence the crimson).
Steppemoor: The Unicorn of Steppemoor is just a bit of army metalwork - Horse Armor includes a horn for charges. however, the horse is so important here, that it's the crest. In addition, Xerian influences mean the Xerian religion (which regards Horses as Sacred) has taken root here.
Frostlands: The Frostlands aren't actually the coldest duchy. Their coat of arms shows a river (the Grifenfjord) and the so called Snow Griffin, a legendary animal that took the uniter of the clans to great victory, allowing him to rule from the Frostlands to Griffindale.
Icelands: seriously, seriously cold. Reinforced by the mainly monotone shield - it just looks cold. The red diamond represents the Frozen Flame, a ruby so brilliant it has been the symbol of the overlord of the Icelands (fun fact: it's always a different flame)
Marshlands: it seems odd that the Marshlands border the driest area of the empire. This has something to do with a supposed event way back in the day, causing the marshlands to be perpetually wet and the area to the south to be perpetually dry. the two waves represent the rivers Gauntlet and Armor, while the fleur de lis represents the local vegetation. Yes, it's blue.
Imperial Pale: The grand seat of the Empire. The Lion is the current dynasties' symbol, though also reinforcing the fact that there are lions just to the south.
Imperial Estate: The "Reserve" of the high lords, mostly just endless woodland. The Wolf symbolizes the main fauna to be found here.
Deshret: Having walked over to the empire from the Shahan Emirate, it was allowed to keep it's culture and pretty much everything, still having a unique status with the empire. Therefore, it has a variation of the Shahan flag.
Sandstream: These rebellious Deshreti were conquered 70 years ago. their new, Imperial ways show a flag with a Cobra - the rebelliousness. The colours of the background are said to resemble the endless flat desert.
Emperors are chosen according to specific tasks set out before them by the duchies; should one not complete a task, one is unfit to rule.
Griffindale: Must hunt down the eagle that resides in Grifenburg (Eagle's Castle)
Artania: Must perform a pilgrimage across the Wall of Artania
North Artania: Must light a secondary fire at the top of the lighthouse using a barrel of wine, and no wine may be spilt on the way up.
Xerian (pronounced Chierian) Pale: Must be able to read the Legacy of Alessor, a book in ancient Xerian
North Bloodfangs: Must sacrifice something of great value (pride) to the crow
Bloodfangs: Must walk the Emperor's Path
Steppemoor: Must tame a Unicorn with bare hands
Frostlands: Hack through the enternal ice
Icelands: bring the old Frozen Flame, and mine a new one with your bare hands
Marshlands: Find the dry lands (is actually easier than it seems)
Imperial Pale: bear the crown with ease (always last)
Imperial Estate: be elected by the Lords (always first)
Deshret: meditation in the desert for an hour
Sandstream: there will always be a rebellion on somewhere. the new emperor must end it.
In short, if you just chicken out when they crown you, you don't get a second chance.