As promised, a quickie entry for Valdemar and the Heralds. This is all off the top of my head; once I get to the books in which these things are fleshed out more, I'll revise my notes as needed.
The nation of Valdemar was founded about 1,000 years after the Cataclysm in which Urtho destroyed himself and his evil enemy Ma'ar.
Valdemar is named for a man who led a band of freedom-seekers into the West, fleeing the reach of a great Empire. His followers named him King, and he and his closest advisors asked the gods for help in ensuring that only good, honest people become future leaders of the young nation.
The gods answered by sending forth magical creatures that look like pure-white horses with blue eyes and silver hooves, creatures called Companions. They are at least as intelligent as humans--and probably more so, given that they are god-touched (and, we find out later, they're usually reincarnated Heralds).
The Companions Choose individuals who are to become Heralds, the best of the best. Heralds aren't Chosen by class, social standing, education, religion, or other similar qualities, but rather by traits that will make them good Heralds, and therefore good representatives of the government and people of Valdemar. There are civilian members in the government in Council and advisory positions, but only a Herald may become King or Queen.
Heralds are kind of like the Jedi Knights in "Star Wars"--they're a little bit of everything. Some Heralds are assigned as circuit-riders; it's their job to ride from village to village, bringing news and information about new laws and passing judgment on disputes or criminal matters. This duty is typically assigned to trainees as their final 'exam'--they ride the circuit with an experienced Herald, first observing how things are done, then taking the reins and doing it themselves.
Other Heralds become advisors; for example, the Herald second in rank only to the monarch is called the King's Own (or Queen's Own) Herald. This person is close to the monarch--a confidante, a friend, the one person the King or Queen can talk to with absolute trust. It's not unusual for the Monarch's Own Herald to be a spouse.
Other jobs would include spying, diplomacy, or messenger relay.
In times of war, Heralds are attached to the military both as fighters and leaders. Much of their training centers on tactics, strategy, and fighting with common weapons (swords, knives, archery, etc.) or magic (if they have such abilities).
For some 500 years after the end of the "Last Herald-Mage" trilogy, there are no Herald-Mages--just "plain" Heralds. The difference in the two is, of course, the use of classical magic (spells and manipulation of magical energy) over what Lackey calls "Mind-magic" (think ESP-type stuff like telekinesis, fire-starting, Mindspeech, and ForeSight for example).