Wyrmguard

The Wyrmguard are the Guardian's shocktroops in Ultima IX. They can be easily identified by their dragonwing-armour (hence the name), and are beasically the army of the Guardian in Britannia. They are mostly armed with broadswords and seldom bother with shields. Also some of them have learned the art of dragon-riding.

However, it is not explained:

a) from where they come.

or b) why the Guardian hadn't used them to conquer the land.

In the fan-written Dialogue Patch however, it is made clear, that these are soldiers from another world already conquered, making them most likely soldiers from Atarka.

Trivia

 * Wyrmguard Armour can also be used by the Avatar (and no one cares!).