To defeat the ghost, first cut the strings holding on to the sword and the ghost will come and take the sword. He is invisible, so turn into the wolf and turn on your senses. Wait until he tries to hit you and dodge it. Then run up and attack him. He will turn visible so turn into human and shoot him with your bow and arrow. The ghost will come down. Now (in human form this time). wait till he tries to attack you. And then attack him back. Keeo repeating this until the ghost dies. (note) if he is invisible turn into the wolf. If visible turn into human.