Sentence:  The marquis, in obsession for his wife, / Longed to expose her constancy to test. / He could not throw the thought away or rest, / Having a marvellous passion to <WSD>assay</WSD> her; / Needless, God knows, to frighten and dismay her, / He had <WSD>assayed</WSD> her faith enough before / And ever found her good; what was the need / Of heaping trial on her, more and more? 
Meaning of the word marked with <WSD> tags:  To test the abilities of (someone) in combat; to fight. (15th-17th c.)