as > [he was] like

8 Which foe with double battery does assail;

battery > {Battering; assault with many blows or missiles}

9 Them on its bulwark bears, and bids them naught avail.

bulwark > rampart, ramparts bids > ?proclaims to, ?tells (assuming that "naught avail" is intended to be read in quotation marks, i.e. as a retort: "Naught avail!", "Do your worst!")

208.36

So stoutly he withstood their strong assay,
2 Till that at last, when he aduantage spyde,
His poinant speare he thrust with puissant sway
4 At proud Cymochles, whiles his shield was wyde,
That through his thigh the mortall steele did gryde:
6 He swaruing with the force, within his flesh
Did breake the launce, and let the head abyde:
8 Out of the wound the red bloud flowed fresh,
That vnderneath his feet soone made a purple plesh.

1 So stoutly he withstood their strong assay,

So > Thus, in that manner stoutly > bravely, unyieldingly assay > assault

2 Till at last, when he advantage spied, 3 His poignant spear he thrust with puissant sway