The three major themes in the movie Excalibur are Magic,Power, and Fate

The entire story of Excalibur is based on three things which intertwine with each other. Those three things are magic, power and fate. Excalibur would not exist with out the magic of the all-powerful Merlin; the town of Camelot would never been created with out the power and strength of Arthur and his men ; and furthermore with out fate Arthur would have never have pulled the sword from the stone. With out these three things …

…In short, magic, power, and fate played a huge role in "Excalibur", there is no doubt about that. Although they were the center themes of the movie, they can easily be the center themes of just about anything. Without magic, Excalibur would never have been created and used by Arthur to defeat the slightly misguided and evil Morded. Without power, there would be no great Kingdom of Camelot. Without fate, nothing would have ever happened.