Well,this is Darth Vader from episode 6. However he is not holding back. In 6 he held back. Luke would have been dead in about 3 minutes or less. But, i don't know the Lukes. This may make me sound like I am new to Starwars, but what is the difference between them?
Freedon Nadd conquered one planet (Onderon)... pretty much alone... and named himself king. In episode 6, Luke had a hard time even getting to cut Vader's arm off when Vader was only using about 1/8 of his power. Why does everyone think that Luke can kill everyone?
ROTJ Luke Skywalker - He is pretty talented, even at the Knights stage he knew how to block Force lightning.
DE Luke Skywalker- He got even stronger than ROTJ Luke. Killed Darth Sidious' clone, which has Darth Sidious' clone inside...and discovered a lost knowledge of the Jedi and used the Emperor's libary to feed his mind with more knowledge
NJO Luke Skywalker - He became a powerful Jedi Master and discovered new Force abilities. He even could control gravity and could form blackholes. He also killed 1000-10000 Yuuzhan Vong in one duel. He was explained when fighting all these enemies the center of the Force. Energy that could not be stopped. He also defeated the Surpreme Overlord, which is a match for many Jedi.
Darth Vader could take them on his own. But now since were talking DE Luke...he could kill Freedon Nadd....Kyle dies from Vader and then Luke has to fight Vader again, but this time Vader's not holding back so...I think were looking at one of the greatest battles of Star Wars again...Don't know but Luke could probably take Darth Vader if he's not holding back...DE Luke anyway.