Diplomat

Diplomats were mediators, those with the skill to help retain the peace.

Ambassadors
An ambassador was a very high ranking diplomat who might speak for a samurai, creating contracts, and lending aid. They were considered part of the diplomatic corps.

Emissaries
An emissary were dignitaries of a daimyo assigned to a very specific task, as carrying a message, so the post was unlikely for a courtier.

Courtier
Courtiers were the lowest rung of diplomats. They were expected to speak for visitors of the court, and know the inner workings of high culture. They had many attendants, and spend much of their time in discussion and argument with others.