The training wasn't so much to make him a fighter, just to make him a Jedi, so he could resist the lure of the Dark Side.
Expect at the end he really didn't resist the lure of the dark side. Without him trying to strike the Emperor down his Father never would have dueled him. Without him channeling hatred of His Father taking his sister and turning her to the dark side. He never would have unleashed those fury of attacks.
I understand the ending of him jumping around and cheering and trying to save his Father. Yet when it counted he used his emotions. As a full Knight, he channeled that. Maybe at the end he stopped but short term he did what Sith did and used his emotions to help him win.
How does that make him better then a Sith, expect he didn't keep on using his emotions?