If the Warden/Hawke is a mage...
Although apprentices do not know the nature of the Harrowing, all of them understand its consequences: They either pass and become full mages, or they are never seen again. Those who fear to undertake this rite of passage, or those who are deemed weak or unstable, are given the Rite of Tranquility instead.
The actual procedure, like the Harrowing, is secret, but the results are just as well known. The rite severs connection to the Fade. The Tranquil, therefore, do not dream. This removes the greatest danger that threatens a weak or unprepared mage, the potential to attract demons across the Veil. But this is the least of Tranquility's effects, for the absence of dreams brings with it the end of all magical ability, as well as all emotion.
The Tranquil, ironically, resemble sleepwalkers, never entirely awake nor asleep. They are still part of our Circle, however, and some might say they are the most critical part. They have incredible powers of concentration, for it is simply impossible to distract a Tranquil mage, and this makes them capable of becoming craftsmen of such skill that they rival even the adeptness of the dwarves. The Formari, the branch of the Circle devoted to item enchantment, is made up exclusively of Tranquil, and is the source of all the wealth that sustains our towers.
—From On Tranquility and the Role of the Fade in Human Society, by First Enchanter Josephus.
If the Warden/Hawke is not a mage...
The Tranquil are the least understood but most visible members of the Circle. Every city of respectable size boasts a Circle of Magi shop, and every one of these shops is run by a Tranquil proprietor.
The name is a misnomer, for they are not tranquil at all; rather, they are like inanimate objects that speak. If a table wished to sell you an enchanted penknife, it could pass as one of these people. Their eyes are expressionless, their voices monotone. Incomparable craftsmen they might be, but they are hardly the sort of mages to put ordinary folk at ease.
—From In Pursuit of Knowledge: The Travels of A Chantry Scholar, by Brother Genitivi.