So the sword gets back to the giants again.
Swipdag's dead foe Halfdan left two young "avengers", Hadding and Guthorm, whom he seeks to slay.

But Thor-Brache gives them in charge of two giant brothers.

Wainhead took care of Hadding, Hafle of Guthorm.
Swipdag made peace with Guthorm, in a way not fully explained to us, but Hadding took up the blood-feud as soon as he was old enough.
Hadding was befriended by a woman, who took him to the Underworld--the story is only half told in Saxo, unluckily--and by Woden, who took him over-sea wrapt in his mantle as they rode Sleipner over the waves; but here again Saxo either had not the whole story before him, or he wished to abridge it for some reason or prejudice, and the only result of this astonishing pilgrimage is that Woden gives the young hero some useful counsels.

He falls into captivity, entrapped by Loke (for what reason again we are left to guess), and is exposed to wild beasts, but he slays the wolf that attacks him, and eating its heart as Woden had bidden him, he gains wisdom and foresight.
Prepared by these adventures, he gets Guthorm to join him (how or why the peace between him and Swipdag was broken, we know not), and they attack their father's slayer, but are defeated, though Woden sunk Asmund Swipdag's son's ship, Grio, at Hlessey, and Wainhead and Hardgrip his daughter fought for Hadding.
Hadding wanders off to the East with his foster-sister and mistress and Hardgrip, who is slain protecting him against an angry ghost raised from the Underworld by her spells.

However, helped by Heimdal and Woden (who at this time was an exile), Hadding's ultimate success is assured.
When Woden came back to power, Swipdag, whose violence and pride grew horribly upon him, was exiled, possibly by some device of his foes, and took upon him, whether by will or doom, a sea-monster's shape.