Atlas is a Colorless Magic tome and a weapon skill introduced in Fire Emblem Heroes.
Weapon Stats
Fire Emblem Heroes
Etymology
Atlas in Greek Mythology is the Titan of Endurance and the son of Iapetus and Clymene who allied with the titans during the First Titanomachy. After he was defeated, Atlas was condemned to hold the sky up for all eternity. He's also said to be skilled in philosophy, mathematics and astronomy.
Gallery
Marianne casting Atlas in Heroes.