The thing about Jinx is that it would be difficult to implement. I'm almsot positive that the duration of all spells/buffs are set in stone once they are cast. Depending on if the debuff sticks fully or is a partial resist determines the overall duration it's just that with a debuff, unlike a nuke it's impossible to tell if it's a partial or half resist until the effect actually wears off. For Jinx to work it would need to be an enfeebling spell itself that all spells cast AFTER it would have a duration boost. This is why almost all equipment that 'Enhances X Ability" needs to be worn either PRIOR to using the ability, or prior to the ability's effect activating(as is the case with Saboteur and RDM AF3 hands).