jollyjim311
Scruffy Nerf Herder
Luke, as of ROTJ, is actually very good. The novel goes into some additional detail.
"Vader was impressed with Luke's speed. Pleased, even. It was a pity, almost, he couldn't let the boy kill the Emperor yet. Luke wasn't ready for that, emotionally."
"It was in his hands, now, he knew it was: he could take Vader. Take his blade, take his life. Take his place at the Emperor's side. Yes, even that. Luke didn't bury the thought, this time; he gloried in it. He engorged himself with its juices, felt its power tingle his cheeks. It made him feverish, this thought, with lust so overpowering as to totally obliterate all other considerations. He had the power; the choice was his. And then another thought emerged, slowly compulsive as an ardent lover: he could destroy the Emperor, too. Destroy them both, and rule the galaxy. Avenge and conquer. It was a profound moment for Luke. Dizzying. Yet he did not swoon. Nor did he recoil. He took one step forward. For the first time, the thought entered Vader's consciousness that his son might best him. He was astounded by the strength Luke had acquired since their last duel, in the Cloud City - not to mention the boy's timing, which was honed to a thought's-breadth. This was an unexpected circumstance. Unexpected and unwelcome. Vader felt humiliation crawling in on the tail of his first reaction, which was surprise, and his second, which was fear. And then the edge of the humiliation curled up, to reveal bald anger. And now he wanted revenge. "
"He must teach this boy a lesson he would never forget, or die learning."
"He rushed to his father with a frenzy he'd never known. Nor had Vader. The gladiators battled fiercely, sparks flying from the clash of their radiant weapons, but it was soon evident that the advantage was all Luke's."
So, according to both Vader and Luke, he had the ability to beat the Emperor (these may not be completely accurate, seeing as how they are not from a narrator, but, they do speak a lot for Lukes power). Also, Vader wasn't going easy on Luke, "he wanted revenge". We know Vaders power, we know he's a beast. Luke beating him isn't a black mark against Vader, it's a showing of just how powerful Luke had become. He was trained to become very powerful, very fast, by Yoda. It was desperate, but, it worked.
"Your hate has made you powerful!" -Emperor.
"The young Jedi was at once confounded and in agony -he'd never heard of such a power, such a corruption of the Force, let alone experienced it. But if it was Force-generated, it could be Force-repelled. Luke raised his arms to deflect the bolts. Initially, he was successful - the lightning rebounded from his touch, harmlessly into the walls."
Luke, using only his hands, could deflect Palpatenes lightning briefly which, according to the Ultimate Visual Guide (Page 21) "is a challenge for even the most powerful Jedi Masters to deflect such bursts," and , seeing as how this is ROTJ Palpatine's lightning, deflecting it for any amount of time is impressive.
Also:
"He wielded it now as if it were fused to his hand; as if it were an extension of his own arm." -In reference to Luke using his lightsaber.
Luke is able to show his skills with the force in ROTJ when he effortlessly subdues two guards and when he performs a mind trick.
Luke shows us two great fights against Vader.
Luke takes out around 20ish mercenaries on Jabba's sail barge.
Vader comments that Lukes "Skills are complete" in ROTJ.
Luke has Luke doing things like inspire awe with his speed, kicked thugs off swoop bikes while deflecting fire behind his back, used mind tricks, and has shown Vader that his power is now incredible (all in SOTE).
He also lifted up C-3P0 and moved him around for an extended period of time, with no hand gestures or signs of strain.
Blah.. I'll type more on this later...