Asgardr, divine guard, may be most probably an allusion to the abode of the gods, Asgard, the abode to which the rainbow-arch Bifrost was the access, trod, according to the grand death song of Eirikr Blödaxe, by the spirits of the courageous dead on their way to feast in the hall of Odin." (History of Christian Names, Yonge, 1884)

... Where a name has no well-recognized English equivalent, I have therefore adopted the modern Norwegian form, which usually differs from the ancient, in having dropped a final letter.  Thus Sigurdr (which with an English genitive would be Sigurdr's) becomes in modern Norwegian Sigurd, Eirikr, Erik, etc. (The Story of Norway, Boyesen, 1894)