From The Heretic Knowledge Vault
The Viradior are, more or less, the equivalent of a Special Forces/Royal Guard group within Elven society. Whether or not this is specific to one of the sub-races or prevalent to all is not known.
During the rise of the Half Elves in importance to the Elves, humans were forced into a more manual labor role than in previous times as the Elves focused more time into training and raising the current half elf generation. Eventually, the only humans that received training were the guards and the Viradior were assigned to train them. This was mainly due to the demand of human gladiators and duelists because of elves who didn't want to have to fill out the necessary paperwork and cut through the bureaucracy to setup official duels between each other. Today they seem to function as a ceremonial guard. They have cool armor, apparently.
The Viradior were introduced here, during Sarine Elle's history lesson. Sarine was one of the Viradior way-back-when. Misa, who's still undergoing character development (as befits her elf-style infancy of merely 1500 years of age), is one of them now. They reappear here, as the Elven Council is busily combing them for volunteers crazy enough to go into the outside world and deal with the goddess on the loose. There appear to be Viradior among the honor guard that go to Tsuirakushiti with Rarune. One or two are also in the elven patrol that intercepts Sarine and the Amraphels outside Praenubilus Astu, at which time Sarine notes disapprovingly (if thankfully) that the Viradior seem to be losing a bit of their ancient arrogance; at least they're easier to face down now than in the Good Old Days. Finally, a Viradior named Gilliam shows up in the grand fight scene at Praenubilus Astu as the Anilis-enhanced Ian (accompanied by the reluctant Meji) starts on his program of elf-o-cide. The last shoe certainly hasn't dropped yet on this battle.