Luke was never trained to be an actual Jedi. he was trained by Yoda and Obi-wan to be a sort of emotional weapon against Darth Vader, ensuring that he would bring balance to the force.
They trained him just enough to survive a fight against Vader, until he could force Vader to turn on his master.
20 years of resentment towards his master in his role of turning Vader to the dark side leading to the death of his wife, brought to a final resolution via Luke.
Luke supposedly learned how to be a real Jedi after the movies in the EU stuff, but after that he just fought scrubs, so who knows