I think I like his training on Dagobah better the way it is actually. We can naturally assume that Luke has been training with his saber, likely on his own beforehand and some with Yoda later.

But I like that the main focus of his training seems to be mental/spiritual. Yoda knows that Luke will eventually find out who Vader really is, and wants Luke's psyche to be able to withstand that without losing his cool or succumbing to the same failings as Anakin.

It seemed apparent to me (before the PT) that Yoda and the Emperor both had reached a level of force prowess where a saber was no longer necessary. Yoda of course would want Luke to be able to defend himself, but his main focus should be mind over matter.

Kind of like the Bride's training in Kill Bill 2, most of it is non-combat.

Reliance on weapons is also one way in which we see growth in Luke between ESB and ROTJ. Three times in ROTJ we see Luke in a threatening situation unarmed, having willingly given up his saber, once in each act.