I think we'll see equipment that is aligned to one or more jobs, and stacking gear for certain levels of this alignment would unlock abilities. Think of it kinda like how wearing a sea torque can let you use a WS before you've actually earned it if it pushes your skill high enough, except you get +skill on all equipment and all abilities and spells would be granted that way. Then you put a delay between equipping a piece and its effects kicking in to stop people from gear swapping constantly.
Weapons would obviously grant the largest boosts, with other equipment available to fill in and round out.
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