no where in there do I see or feel anything about growing past the need for his lightsaber and I can’t make any sense of that in context to the scene. It’s not like he thinks upon defeating Vader that he’s ascended to a higher level and could fight the Emp without his saber
He realizes that fighting isn’t the way. If it costs him his life, so be it, but he’s trusting the Force now and not himself. That’s the “leveling up”.
Like many elements of ROTJ, it’s murky and not perfect and not everyone will agree, but that’s my take:
He either tosses it because he’s just ‘moved past it’ so to speak, or he’s just being stupid. 😉
He’s being offered a position as right hand man to the evil ruler of the galaxy. By his gesture he’s saying, “You DON’T have my sword. Kill me if you like, but I will not stand by your side”.