[Note: Sigurd is a figure in Germanic mythology]
It is my opinion that this reborn Sigurd was none other than Adolf Hitler. Like Sigurd he was stabbed in the back but faithfully fulfilled his mission as the Norns decreed. He had many dragons, many enemies who sought to slay him and his Volk. Indeed German war time propaganda did use the image of the slaying of the dragon as symbolic of National Socialism's war of attrition against bolshevism. He knew he had to slay for failure to do so would have resulted in the destruction of the Aryo-Germanic peoples.
Likewise Thunor at Ragnarok will go forth to slay the serepent at the end time although He Himself will be slain by its venom. Neverthless He will continue to live through His sons Magni and Modi.