she > [Fortune]
2 To adorn your form according your desert,
your desert > [to your merits]
3 Their blazing pride you would soon have blended,
blended > stirred up; hence: rendered turbid, spoiled
4 And stained their praises with your least good part;
stained > {Deprived of colour and lustre} praises > [the praises they receive; cf. 111.7:6] part > quality; accomplishment
5 Neither should fair Claribella, with all her art,
Claribella > "Clear and Beautiful" (Latin. This spelling is adopted in view of 204.28:3, and to differentiate her from the "Claribell" in 612)
6 Though she your lady be, approach you near: 7 For proof thereof, this evening, as you are, 8 Array yourself in her most gorgeous gear,