That > [So that] dismayed > overcome, defeated; dismayed
4 Nor ever to them yielded foot of ground 5 All had he lost much blood through many a wound,
All > Although
6 But stoutly dealt his blows, and every way
stoutly > bravely, robustly
7 To which he turned in his wrathful stound
stound > peril, time of peril; fierce attack; also (mainly northern usage): roaring, violent noise; so: uproar
8 Made them recoil, and fly from dread decay,
fly > flee decay > death
9 That none, of all the six before, him dared assay.