As all leaders should, Beowulf has a self-confidence that is necessary to perform his duties. It allows him to inspire confidence and loyalty in his followers and to make decisions without hesitation. Beowulf also has a great deal of strength. This reinforces his image as a protector, allowing the people to feel safer and creating a sense of peace by preventing fear and panic.
These things, however, that make him a good leader and a good warrior bring with them arrogance and pomposity. Beowulf thinks a lot of himself. This leads him to believe that he can do everything on his own. He rarely delegates or asks for help, but moves on by himself and does it all. As we see in the last adventure, if Wiglaf had not insisted upon accompanying Beowulf, then the dragon would have triumphed. Wiglaf knows what Beowulf does not - even a strong leader must have aides.