Is usually a symbol of spiritual death how does this fact add significance to Beowulf and last night with the dragon?

For the Geats, Beowulf is a reliable lord. "there was none else like him alive in his day, he was the mightest man on earth highborn and powerful". Indeed many feud battles he overcame. Thus no one dares to approach the land of the Geats.

During his life, there was a reciprocal feud between the Swedes and the Geats. One fact is that Eanmund and Eaddgils, the sons of Ohthere, were driven into exile by their uncle Onela, the king of the Swedes. they were given refuge by Hygelac's son Haerdred, who succeded his father. Onela invades Geatland and kills Heardred; his retainer Weohstan kills Eanmund; and after the Sweeds withdrew.

By this time Beowulf became a king. Eadgils, supported by Beowulf invades Sweden and kills Onella.

Not surprisingly, the death of Beowulf, the defender, signifies a threat for the Geats. in his funeral, it is said "Now war is looming over our nation, soot it will be known to Franks Franks and Frisians, far wide, that the king is gone". it is said also " Nor I expect peace or pact-keeping of any sort from the Swedes"

reference:

according to The Noron Anthology by Stephen Greenbaltt, vol I