George Lucas disagrees with you he layed down the law that you cannot master both light and dark g canon overwrites whatever is said in the revan book so revan did not master both since its impossible.
What revan did was become one with the force which is not mastering both light and dark hell revan was not even a master of the dark side or light side. What made revan amazing was his leadership abilities and his charisma not his prowess with the force.
If the exile was not there revan would of been killed by the emperor.
I find Revan to be a special case since he literally lived two lives. He had knowledge of the darkside and had mastered it in one life but because of his alignment as a jedi he could not use its abilities to their fullest. Luke had great knowledge of the darkside and probably could have performed many powers if he was a sith. I think defeating Malek and being at least able to put up a good fight against the emperor of the sith puts him at master level for the light.