Yoda seems to be the only one wise here.

This is why Leia was not needed to be, 'the other' as Anakin works so much better.

Ben's first lesson is how to spin a sword and he gives a lightsaber to Luke the first time he meets him.

Yoda discourages violence and never asks Luke to kill Vader only to face him, to face his fear.

Luke remembers Yoda's lesson in the cave and throws away his sword.

This actually lets Lucas off the hook for not fully training Luke because Anakin is the 'fully trained Jedi Knight with the Force as his ally' that defeats Vader and his Emperor.

PT Yoda leaps around and spears Clones through the chest.