to weet > to wit
2 That ranged abroad to seek adventures wild,
abroad > broadly, widely; in different directions
3 As was his wont in forest, and in plain; 4 He was all armed in rugged steel unfiled,
unfiled > [not smoothed with the file]
5 As in the smoky forge it was compiled,
compiled > constructed, hence: fashioned, hammered out
6 And in his scutcheon bore a satyr's head:
scutcheon > escutcheon, shield satyr > (Satyrs are horned forest spirits, man-like above and goat- like below, usually portrayed as more or less lustful. In Roman mythology, Satyr, one of the satyrs, is a companion of Bacchus with long, pointed ears, behind which are the stumps of horns, with the tail of a goat, bristly hair, and a flat nose. See 106.20 ff.)
7 He coming present, where the monster vile