Weapon swap for cast on crit

Am I missing something here? The idea would be to be able to generate energy with a skill assigned to weapon set 1 but having the actual cast made with weapon set 2

If I assign cast on crit to set 2, then it's not reserved while using weapon set 1. If I assign it to weapon set 1 and 2, then it's not switching. If I assign cast on crit to weapon set 1 and the triggered spell to weapon set 2, then I have the 'missing socketed spell' warning...

Is it just not possible?