Legate
Definition: an emissiary or envoy
This is a term most closely aligned with the Catholic church of the Italian renaissance. A legate was a representative of the church with decision-making powers, since geography and transportation at the time prevented easy communication with a central authority.
Several definitions compared it to plenipotentiary.
Why I Looked It Up
The Medici referred to someone as “the Cardinal legate.” At first I thought it was simply an Italian title, but the book didn’t italicize “legate,” as it did with Italian words.