Sentence:  [S]ince by our commission we are not <WSD>warranted</WSD> to treat but with the noblemen named by his majesty with the advice of the peers, and are particularly <WSD>warranted</WSD> to make exception against the earl of Traquair, for his malversation in the matter of the assembly and parliament, [...] 
Meaning of the word marked with <WSD> tags:  To authorize; to give (someone) sanction or warrant (to do something).