The one thing Hereward does not do is kill a dragon but then, nobody had seen a dragon around Ely. It would be hard to make that one up. However, Hereward did fight a bear and a giant/ogre, goes on a bridal quest with an Irish prince to obtain a Cornish princess, and wins special items through his battles. He too had all the accouterments of Siegfried: the sword, cloak, corslet, helmet, and a horse. He is missing a ring but he does repudiate his first wife, with whom he has a daughter, and takes a second wife. His singing performances remind me of Volker. Who would not like Volker? Richard of Ely does not say he dies because of an act of treachery but Geoffrey Gaimar does.
Hereward was not felled by one warrior sneaking up from behind but four(mind you it may have taken four Normans to make one Hagen) but, with Hereward unable to reach his sword, he does take up a shield like Sigurd in Volsungsaga and kills a man with the edge of it. Siegfried only wounds Hagen with the shield instead of killing him like Sigurd kills Guttorm. Gaimar has nothing to do with the account in Gesta Herwardi; they are too different but one has to wonder if one of the stories that Leofric was reading while he was composing his history of Hereward was not one of those early versions of The Song of the Nibelungs. It is an intriguing thought.