Trial of the Magians is a system in Final Fantasy XI primarily for obtaining, augmenting and upgrading weapons and armor to a higher level. The system is also used to unlock the job-specific Emotes. In order to undertake a trial, the player must hand over the equipment to be augmented or upgraded to the appropriate moogle, who will inscribe the trial information on the equipment, hand it back, and tell the player the task that must be completed a set number of times to complete the trial. Example tasks include killing a specific Notorious Monster, killing monsters of a certain family (optionally with a specific method, or under a certain Weather), using a certain Weapon Skill a certain number of times, or turning in a specific number of a certain item to the Delivery Crate at the side of one of the Magian moogles who supervises the trials. When the trial is completed, the equipment must be handed over to the moogle again, who will work special Moogle magic on it and hand it back.

The most important use of the Trial of the Magians is to upgrade relic weapons, Mythic Weapons, and Empyrean Weapons from level 75 to level 99. However, by opening the Splintery Chest at the side of the lead moogle, players may obtain free weapons that may be upgraded and specialized using the trial system.