I think the turning point of the legend of Sigurd and Gudrun is in fact signaled by A DELIBERATE METRICAL ERROR, WHICH, OF COURSE, YOU ARE SUPPOSED TO NOTICE as a sign of serious emotional disturbance.
It is page (got to find it, wait for me) p. 154, line 4 of the second stanza on that page, "all unfulfilled". This must take stress on the first two syllables. But in a second half-line, the second stress must NEVER take stress and alliteration, as it does here. Shock horror. But it is a moment of shock horror, as Sigurd gets his memory back and realizes he has betrayed Brynhild.
"Что наверху, то и внизу".