In ROTJ Luke:
- has had time to construct a new lightsaber (not likely an easy or quick task, especially considering there’s no one around to teach him).
He could have learned that on Dagobah. Actually that would be the most logical explanation.
- has learned far greater control of the force now and new abilities, one which he would have had to figure out on his own as Mala pointed out. He uses these effortlessly, including when he whips his lightsaber up into his hand from the Emperors chair.
He did that already in TESB when he fought Vader.
- has far greater control over his lightsaber, so much so that combined with his new focus with the force that he can consistently while under pressure deflect/reflect laser fire now.
He learned that on Dagobah when he trained against 4 or 5 of those training droids.
- comes across from the get go as a changed person, one that is now calm, focused and confident in his control of each situation. He has matured and wisened in many ways, people clearly look to him for leadership now where before that was Han and Luke was the whiney young guy.
He is changed.
And it can be explained easily with what happened on Dagobah and on Bespin. That would change everybody.
… is it even known to any of the rebel characters where Han has been taken? I can’t recall a time in TESB where any of them would learn about this, so on top of the rebel forces needing to regroup and get themselves in order again after the evacuation from Hoth, the gang also had to try and find out which system, planet and group had Han after probably initially presuming the Empire to have him.
They know that Jabba has Han. Vader told that to Lando.
Finding where Jabba is, ain’t that difficult. I just looked up an earlier poster here:
“hire someone to negotiate my deal with Jabba, probably an old acquaintance, who can be trusted with this for the right amount of money, and merely provide escort as a ‘mercenary bodyguard’.
Contact Jabba’s nearest ‘representative’ and present an offer with one condition, that I only make deals with Jabba himself.
Make the offer irrefusable, success is guaranteed. You can always count on greed.
Now I have Jabba’s location, and free pass, and don’t have to travel around the galaxy planet to planet and infiltrate and etc…
When deal is completed, ask Jabba for a job. With good credentials Im in.
Call Luke.
How long does this takes?
Couple of days, a week maybe, depending on travel distance”
So basically nothing here suggests that months need to pass, yet alone a year or more.