Do they have a connection with the void? Do they use the void like certain Thaumaturges/Black Mages? What is this 'Darkness' that they channel? Is it just a manifestation of their darker emotions? If so then anyone who can channel aether via emotions can be a Dark Knight?
I really want to understand where Dark Knight's powers come from, most other jobs seem to have good explanation, but it seems a lot of people or maybe Dark Knight itself is piggybacking on the "It is just an expression of emotions" similar to like Warriors.
Is it possible this Darkness we tap into is the same as what the Ascians tap into? Some form of energy from Zodiark? Or could it possibly be the void and voidsent that are behind these powers?