4 Well searched, eftsoons he gan apply relief
searched > probed, examined eftsoons > forthwith gan > did
5 Of salves and medicines, which had passing proof,
passing > surpassing, excellent proof > proven worth; hence: efficacy
6 And thereto added words of wondrous might:
thereto > moreover, also
7 By which to ease he him recured brief,
ease > (Sb.) recured > cured, restored brief > rapidly; briefly, temporarily
8 And much assuaged the passion of his plight,
passion > suffering