This has a spoiler or two in it. You probably already know about them...
Luke never learned or trained to be a full Jedi like his father, Anakin, AKA Darth Vader. Anakin was trained by the great Obi-Wan Kenobi to use a saber properly, and Kenobi really knew his stuff on the glowing sword front.
With no training at all, you have to cut the poor guy some slack.