Trial Weapon refers to a weapon that is used to unlock a new Weapon Skill for that class of weapon. These trail weapons are obtained through quests that were introduced with the Rise of the Zilart expansion and can be opened by players possessing the prerequisite job and Combat Skill for the weapon they wish to obtain.
These weapons have a Latent Effect which is active until 300 Weapon Skill Points have been accumulated using the weapon. Once this latent has been "broken", the weapon can be exchanged for a key item that will allow the player to pop an NM that will grant them access to a new Weapon Skill upon defeat and completion of the quest.
There are 14 Trial Weapons, one for each weapon category (except Throwing weapons, which have no weapon skills):