Luke has no one to teach him further, since there are no others. That is unless spirit Yoda & Obi Wan can train him.
I originally thought (back when RotJ came out), that Luke was a true Jedi Knight and he could now train more (a la all Dark Forces/Jedi Knight video games to follow).
But from what you guys are conceding is that he's not very good, and all he can pass on is his limited knowledge. That's depressing.
Whereas I WANT to believe that Luke was suppose to be as powerful and knowledge in the force by the end of RotJ as Anakin is by Ep 3.
And although his training is accelerated, his ability to master the force so fast is a result of being so strong with the force (stronger than his dad) and the one who REALLY brings balance to the force.
So in the one case we have Yoda 'graduating' a half-assed Jedi and on the other we have Lucas unable to go full out when filming a saber scene.
I think I can live with the latter much better.