Sabo is the second in command of the Revolutionary Army. He was first introduced in a flashback. Sabo is a powerful character, who is able to fight with an Admiral (even though Sabo and Fujitora were just playing).
Sabo can use Armament and also Observational Haki. He possesses a type of Logia Devil Fruit called Mera Mera no Mi, which allows him to create and control flames. He was able to defeat a Vice Admiral and also Jesus Burgess which only a single hit. Moreover, he fought with the whole Marine division in Dressrosa alone.