any person who uses skill and tact in dealing with others and solving problems, especially by compromising rather than arguing or threatening so that everybody involved gets a fair treatment;
(old usage for) a diplomat ( ← ← previous entry),
Whenever the company faces a tough problem with a supplier or customer, the CEO calls in Mr James Dawson, our PRO and the best diplomatist, to tackle the problem, and Mr James Dawson comes out successfully eight out of ten times!
Each time our state has a friction with the neighbouring state over some border or river water issue, the Chief Minister sends in the senior most statesman and his mentor to negotiate with them, and true to his fame, each time the Old Man proves himself an unbeatable diplomatist by negotiating successfully.
In this present world of terror and war-mongering, what we need is not just a politicians who work diplomatically but some truly sincere diplomatists who risk their own lives for the unity and peace of the world by crossing over their own prejudice and the restrictions imposed by their respective nations.