He is the only one who is able to remove a sword stuck in a  tree.
This figure calls for help in slaying seven men, but his son does not  call for help in slaying eleven men. This man is able to cure one of his  sons by observing two weasels that were fighting, then using the herb  that the weasel used to heal each other. He slept with his own sister to  produce that son, (*) Sinfjotli, who transformed into a wolf along with him.  This man is able to stay alive after his sister smears honey onto his face,  letting him bite off the tongue of a shape-shifting wolf that was actually  Siggeir's mother. He is the only one who is able to remove a sword stuck in a  tree. He is the brother of Signy, and his son gained fame for marrying  Brynhilde. For 10 points, name this father of Sigurd.
This figure calls for help in slaying seven men, but his son does not  call for help in slaying eleven men.
Sigmund