Roc-riders were members of a military group of the Ghioz Empire.
After the War in Bant, the Ghioz Empire learned the need to gain an aerial force to counter the dragons in battle. They attempted to recruit exiles and mercenaries (employed during the Third Battle for the sun-shard), but also worked hard to establish an own military force.
Roc-riders fought a number of engagement during the War of the Red Queen and proved to be lethal to dragons (but not invincible).
Riders fought with multiple weapons (especially arrows), but most of the fighting was done by the beak and the talons of the Roc.