Here are descriptions of all the noble houses the players have run across or should know about. They are by far not all the houses involved in this world. But I'm as of yet unsure just which types of houses will have to be brought into the RPG. New houses will likely be added as I go. But until then, these are the ones I have detailed. Houses Nissa, Protectoriate, Banshee, and formerly Magus are the most important noble houses on Lunar.
House Nissa (House Color is black)
House Nissa is the leading family of the Magic Empire and nearly all of them reside in the capital city of Killish from which they can sit on their butts (j/k) and bark orders to all the other noble houses stationed around Lunar. The fearsome Emperor Kargeth is the head of the household.
House Anhaln (House Color is sky blue) Anhaln houses the master artisans of the Empire. Almost anything made and used by the hands originate from House Anhaln. Though Anhaln is capable of manufacturing things such as pottery and silverware, such things are usually bought from commoners unless Anhaln is commissioned for a truly exquisite piece of work. Anhaln's most important duty though is providing weapons for House Protectoriate. Anhaln has a tense relationship with House Nemar since Nemar was formed by a group of warlocks who had broken off from Anhaln.
House Banshee (House Color is green)
This house is very small, but extremely powerful in terms of political affairs. The warlocks of this house are called in for asassinations and other special missions requiring the utmost care. They are fanatically loyal to the Empire and ultimately only answer to Emperor Kargeth himself.
House Desselm (House Color is bone)
House Desselm is a very reclusive house, having had loose ties with Magus (for research purposes) and Banshee (for a ready supply of test subjects). These warlocks have a very gruesome task and specialize in various necromatic arts. Everything from animating the dead to disease control falls under their domain.
House Erde (House Color is brown)
Erde really isn't known for much other than the poor quality of territory it has. It's valuable to the Empire in terms of what's in charge of (watching over the growth and harvest of crops), but unfortunately that doesn't give it much respect among the other houses.
House Flysse (House Color is gold)
Flysse rules over the lands south of the Nanza Barrier. The wide open land stretching east from Reza, to the western mountains and south until the ocean is all their domain. Though it is relatively uninhabited, it suits them just fine, for the space allows them to do what they do best, breed the monsters and other atrocities that serve the Empire's purposes. In addition to being breeders, the warlock hunters of House Flysse are a reknowned group of warriors within the Empire.
House Magus (House Color is silver)
House Magus is the archiving house of the Empire, documenting all of its exploits and storing the Empire's history for future reference. They are also noted for being the leading experts on the research of magic.
Update as of Session#12: House Magus is secretly the driving force behind the new rebellion. According to Lady Mileria, House Nissa has placed one too many demands on them, and so they intend on overthrowing the warlock social system. But as Kadan pointed out, are they really doing it just to better themselves, or for the commoners as well? What was this final straw that made them snap?
Update as of Session#21: It appears that House Magus has fallen under the accusation of House Erde.
House Nemar (House Color is sepia)
Nemar has only recently come into existence, but have quickly earned the favor of House Nissa. They are mainly responsible for the invention and maintenance of the Empire war machines (catapults, ballista, etc.), but they also are in charge of all mechanical contraptions in general.
House Protectoriate (House Color is navy blue)
Protectoriate is in charge of maintaining the army's condition and training of their soldiers. They are strict disciplinarians, and absolute adherences to their rules are demanded of both the citizens living in their territory and the members of their house.
House Terna (House Color is scarlet)
House Terna is responsible for maintaining all the Empire's paperwork. While House Magus deals with research and history, Terna takes care of all the bureaucracy and official government materials. Terna has always been above houses like Erde because of its important work. However, it's considered below the likes of Magus and Nissa because after all, it's still a secretary, no matter how invaluable its work it.
House Zephyr (House Color is sky blue)
Zephyr is the seafaring house of the Empire. Their duty is to patrol the seas and prevent the existence of pirates which would threaten trade between the islands and the continent. The members of House Zephyr are often referred to as the Seamasters because of their control over wind and water. The greatest of them can even influence the weather.
In case you have forgotten (or you didn't read the section on warlocks), in addition to the snake and dagger symbol of the Empire, each noble house has a characteristic aura color. So when a warlock's symbol glows, it is in the color designation of which house the warlock belongs too. For example, House Banshee's symbols glow green, and House Nissa's symbols "glow" black.
Also, policing the people is a duty all warlock houses share regardless of rank. Each house is assigned some amount of territory to watch over and govern as they see fit. The size of the territory is related to the size of the house. And the quality of the domain is related to the rank of the house. Thus dinky little House Erde gets to police a chunk of boonyville Caldor Isle while great big Protectoriate gets the city of Shelladon and the surrounding areas.