Definition of "earst"

So th' one for wrong, the other strives for right,And each to deadly shame would drive his foe:The cruell steele so greedily doth bightIn tender flesh that streames of bloud down flow,With which the armes, that earst so bright did show,Into a pure vermillion now are dyde: […]

1590, Edmund Spenser, The Faerie Queene‎, published 1921, Book I