been > [were] uprear > raise

2 Their beavers bright, each other to greet;

beaver > visor (strictly, the lower part of the face-guard)

3 Goodly comportance each to other bear,

comportance > behaviour; accordance

4 And entertain themselves with courtesies meet.

meet > fitting

5 Then said the Redcross Knight, "Now might I weet,

weet > know

6 Sir Guyon, why with so fierce salience