Main and Sub slots used for Melee Weapons
Weapons are pieces of equipment that can be equipped to either the main or range slots. If the Job Trait Dual Wield is learned, a one-handed weapon may be equipped to the sub slot as well. Different weapons are wielded differently by each job, so be sure to always be using your job's highest rated weapon. Each major weapon subcategory also comes with its own unique set of weapon skills to further their usefulness in battle.
If a weapon of a certain type is listed as usable by a job but not listed as a skill on the job page, then the job can use the weapon but can never gain skillups. Any skill involved would come from a subjob. An example of this is a Paladin and Archery or Red Mage and Hand-to-Hand.
Macro: /equip main "Item Name"
Relic Weapons can be seen here.
Mythic Weapons can be seen here.