Honor. Service. Sacrifice. – Decree of the god, Tor, and the sentinel oath.
Sentinels are highly trained warriors with a dual purpose: to protect civilians from mages, and to protect mages from those who would use their magic for nefarious purposes.
Above all, a sentinel's devotion is to the pantheon of deities which they serve; second to this is their devotion to the general populace; third is their devotion to one another. The control/protection of mages is a sentinel's greatest duty, as it serves all three purposes: it is the will of the gods to control the “unnatural” mages; it is to protect the innocent people from the mages' power; and it is to protect and help their brother and sister sentinels with these duties.
To prevent mages' magic from working upon them, sentinels ingest a metal called hematite.
Sentinel garrisons sentinels operate under the guidance/control of the main religious organization of Aredia, the Circle. A sentinel is in service from the moment s/he is brought to a garrison to the moment of their death; there is no time of service, no contract, nothing to legally release the sentinel from their service, though rarely do they seek another life, as this is usually all they know. They are expected to follow the orders of their superiors without question or hesitation, and if they disobey – for any reason – they can be Forsworn: cast out of the sentinel order, cut off from hematite, and “purged” from the Circle.
Life of a sentinel
Both men and women are allowed to be sentinels; no distinction is made between the genders. Children are generally brought into the sentinel order at a tender age; usually they are orphans or later-born kids of a large, often poor family, who will get compensated for the “loss” of their child. They are given generic names (Initiate One, Initiate Two, and so forth) and train rigorously until they reach maturity, (around 15 - 16 years of age), and go through the Burn. The Burn involves a harrowing test of those skills they have trained for, including survival skills, ability with weapons and combat. However, the Burn is mainly focused on a large ingestion of crushed/powdered hematite, which a sentinel will have to eat on a regular basis for the rest of her/his life in order to resist mages' powers.
In preparation of the Burn, initiates are given minute quantities of hematite as they grow, but the largest dose is administered during the Burn, after they have proven their skills in combat. The thinking is, if the initiate is meant for the rigorous, often difficult life of a sentinel, s/he will be strong enough to withstand the hematite's poisonous properties. Many do not, and die. Some do, and go on to become true sentinels. Most sentinels choose a new name for themselves around this time, which represents their individual devotion to their cause. Since many sentinels are devotees of the god Tor, whose symbol is rock, stone, and mountain, many of their names revolve around that theme.
After the Burn, new sentinels, called "burnies," are transferred to another garrison to begin their life of service. From there, they may remain generic sentinels, or move through the ranks: sergeant, lieutenant, captain and commander. A commander is in charge of each garrison, reporting to the High-Commander in the capital city of Lasath in the Silverwood Province. Each garrison is responsible for guarding a mage bastion, ie: a walled pseudo-city where mages are forced to live.
The sentinels are provided for by the Circle in the way of food, clothing, shelter, and other accouterments of day-to-day life. Generally, the sentinel garrisons are staffed by members of the Circle, though the sentinels also do much of the daily chores. The busier/larger garrisons are supplemented with lower tier workers, commissioned by the Circle.
All sentinels give up ties to their pasts and their families upon joining, and usually choose a new name for themselves once they survive the Burn. Sentinels are forbidden to marry or have children, (the latter being generally an impossibility, given the poisonous nature of hematite), but they may discreetly take lovers of either gender, provided it does not interfere with their duties. It is a said to be the ultimate sign of strength of character and commitment to the gods if a sentinel takes a vow of celibacy, though it is not a requirement for joining.
So that they may not be bribed, sentinels are not permitted to have any dealings with money, (earning, gambling, purchasing, etc); citizens are expected to give them what they need/ask for, and they can contact the Circle for payment. The reputation of the sentinels as being good and pious means that this is generally adhered to. They cannot own property, have contact with or seek out their old families, (though not all obey this).
Sentinels may only kill in defense of citizens, mages, or each other, though if a mage goes rogue they have the authority to end the mage's life. This means that their uses as a military are limited to defense only.
Breaking one of these rules can result in a number of punishments, ranging from increased menial tasks to outright expulsion from the sentinels and the Circle, (Forsworn.) It's considered blasphemy to show kindness to a sentinel who is Forsworn, and rarely will a commoner help them. Usually, they don't survive very long; the withdrawal effects from hematite are severe and often fatal.
While not a “rule,” exactly, sentinels are not encouraged to read, or to learn to read if they are illiterate. Though some sentinels come from higher tier families and are educated, many grew up destitute, with no means to learn how to read. They are taught to “recognize” words for cities, towns, etc, (as found on maps), but the sentinels have their own code system in which they write, (which is what all their personal maps, letters and reports are written in). Generally, sentinels don't read for entertainment. Ostensibly, this is to give them all a “level playing ground,” so to speak, (upper and lower tiers alike), but in actuality it's a way for the Circle to further control them. Reading brings new ideas, and with new ideas come questions about current practices; best to keep the sentinels focused on their duty rather than filling their heads with questions.
Sentinel wear twin daggers at their sides which they are only supposed to use for defense, and carry a sword (embedded with hematite) that is only drawn if they are to kill. They are also trained with bows, crossbows, wilderness survival skills, woodcraft, basic healing, (stitches, herbcraft, etc). Sentinels wear cured leather armor that has been boiled with hematite, embedding the stone within the hardened leather, which further protects them from magic. Very often small bits of hematite are added to the armor, (generally embedded into the leather), allowing sentinels to have a unique design or pattern suited to their liking. A sentinel is given several vials of hematite to use for emergencies, or if they are traveling away from a proper garrison.
Even with a strong constitution borne by years of activity and training, most sentinels do not live past their middle age. The oldest among them are generally in their mid-to-late forties, called "cinders." A shortened lifespan is the result of hematite, which gradually poisons the body and eventually takes its toll. As a sentinel ages and becomes more acclimated to hematite ingestion, more and more hematite is needed to keep a sentinel strong, until their bodies essentially burn themselves out after one too many hematite doses.
Hematite is highly addictive, and if a sentinel goes without ingesting it for too long, (depending on the sentinel's age), s/he will suffer withdrawal symptoms. As sentinels age, more and more hematite is required to give them that same amount of energy, if they can ever achieve it again, but the strain on their bodies becomes too great, and they will die.
Due to the poisonous nature of hematite, conception is rare among female sentinels, and even more rarely is a pregnancy able to be carried to term. Female sentinels can still menstruate. Male sentinels can father children, though it is also a rare occurrence.