Such a unit was in Carthage.
Sacred band Carthage was an elite military unit, created to protect the Republic. Unlike most of the Carthaginian military units, they were formed entirely of Carthaginian citizens as opposed to most of the Carthaginian army, which numbered mercenaries, in fact, they were the only parts of the Carthaginian armies, who were forbidden to join the mercenaries. They were dedicated to Baal, and were listed as heavy infantry. Skill and experience of these soldiers were so high that, despite their small number, Polybius described it: "A bright emblem of Carthage on the battlefield was more master of the situation, one hundred thousand men"
These soldiers were considered sacred because of the oath which they swore when they were accepted into the ranks of the group. Their weapons were the weapons of the temple, and each soldier carried weapons with honor. Sacred Order was easily recognizable on the battlefield, as They wore white clothes, the color of death in the Carthage community.
Specifically, they wore white linen shell, with images of the sun, apparently a symbol of the Holy band, with carry-over into the red on the shoulder folding clasp. It was more like a Macedonian Star (Star Agread). Tunic was yellow. Pterygium had red bars on the main land. Shell also had a red belt and red stripes on the sides. Holy Warriors band also wore
large hoplite shield, painted red.
Tactically, the Holy Order has been trained to take part in the melee, using their shields and spears, as in the classic phalanx. Their forces were often used for disciplinary action. They are often placed in the forefront of the infantry, to only one of their kind could throw a scare on the enemy.
Detachment disappeared during the First Punic War.
("Armies & Enemies of the Macedonian & Punic Wars" Duncan Head)