::Interesting, all of it.  
 ::As for the Scandinavian origin of the name, though, I would guess that an approximate fanciful description of adult human male genitalia was involved, something between a knot, a lump and a knotted lump. Many ancient Scandinavian names have origins that today are not quite rumsrena (approx. "clean enough to be in furnished rooms"). 
 ::The coinage of King Canute II of Sweden shows Kanvtvs, so that’s no help with the main question in this section.