Dual speccing is limited by the 9 skill slots.

You can't just grab another 2+ different persistent gems, due to opportunity cost. I don't know if this is really by design. I can't imagine why that would be.

Which leads me to believe that the game should have 1-2 "persistent gem sockets" for each weapon set. Or even more wild, persistent gems already require spirit, why must they also require a gem socket?

Food for thought.