Full > Exceedingly baleful > deadly, woe-dealing
4 He read, and measured many a sad verse,
measured > traversed, hence: read, read through; also: appraised sad > grievous, calamitous verse > line, versicle; verse
5 That horror began the virgin's heart to pierce,
That > [So that]
6 And her fair locks upstared stiff on end,
upstared > stood erect stiff > stiffly; violently
7 Hearing him those same bloody lines rehearse;
rehearse > read aloud, recite
8 And all the while he read, she did extend 9 Her sword high over him, if aught he did offend.