Jean de Brienne, 1170-1237, Comte of Eu. His shield of arms above are blazoned as:
azure a lion rampant Or
Shown above, the arms of the Kingdom of Jerusalem, blazoned as:
argent a cross potent between four crosslets Or
Shown above, the arms of the Latin Kingdom of Constantinople, blazoned as:
gules crusilly a cross between four annulets within each a crosslet Or
Jean de Brienne was Emporer of the Latin Kingdom of Constantinople, regent for Baldwin of Courtenay until Baldwin reached the age of twenty. Then they were co-rulers in the last two years of Jean's life.
Chosen by fate to play a role which the size of his armies denied him, Jean nevertheless was King of Jerusalem and Emperor of Constantinople and left one of his daughters Queen of Jerusalem and one other daughter the Empress Consort of Constantinople.
He was a Crusader who declined to sack Constantinople in the Fourth Crusade, and went home with his men. He also quit the Crusade against the Albigensians of the Languedoc after the bloodbath at the first city, Beziers. By his deeds he was known as a ferocious fighter and leader of knights, but also known as a man who chose to not wage war against women and children. He was trusted by his peers and by the kings, Popes and Emperors of his day with two of the most important thrones of his era, and with two of the most vulnerable royalty.
For a mere second son, destined to become a clerk, he didn't do too badly.