A thesaurus can allow you to have a stronger connection with your audience, as well as a better understanding of your topic. By learning what other words you can use, you can adjust the tone of your writing or speech, helping you to be as effective as possible.
If you are referring his defeat at the end against the dragon, that is because of his hubris. He was too proud and believed that he could do it alone without his soldiers. This brings his defeat and he realizes that he will die because of his hubris, after which Wyglaf will take over since he was the only one brave enough to help.
