In the Alros and The Torch of Skies game, a Sacred Knight is a very special person who has being blessed by one of the Fairy Queens and is responsible for the protection of the flame of one of the altars of the skies.
A Sacred Knight must also protect the temple where the altar burns, honor and venerate the Fairy Queens and make offering for his respective Fairy Queen.
There is a Sacred Knight for each one of the altars. They all are chaste men, as the only women they have to adore and serev are the Fairy Queens.
The most of them were killed by Lord Dim in the beginning of the Game, only surviving Alros.
If they are not violently killed, they are supposed to be immortal and eternally young.