Alyss a courier and diplomat

How diplomats and couriers are trained is not yet fully known but despite that a lot of hints have been dropped about their training throughout the series.

Couriers are trained in disguise, diplomacy, politics, languages, some self-defense, encrypting messages as well as encoding them to some extent and taught to keep a calm, neutral expression even when it is hard, they are also known to possess some acting skills as demonstrated by Alyss in the Roamers.

The training is said to be every bit as tough and hard as Ranger training, noted by Will in the Sorcerer in the North, and can also be dangerous something the couriers must accept and be aware of.