The sword he decided to use was Naegling(Borrowed from the king). The Dragon was fire-breathing and melted the sword causing Beowulf to battle without a weapon. The blood of the Dragon was poisonous and when he did bite Beowulf, he died. Wiglaf went back to fight the Dragon and later was sent back to the cave to get some of the treasure he won over for Beowulf. Before he dies Beowulf orders a barrow to be made in his name and then names Wiglaf the new King of the Geats.