Mention of Saverill in GR:

"I suppose that depends on who you work for, then. Zachary or his brother. But hear this, Swordmaster, Zachary is the one in power. He was the one named heir by his father, not Amilton, no matter the usual order of succession. What you've done is high treason, and if you get caught and strung up, you will be let off easy, I assure you. If I recall history, there was a traitorous Weapon named Saverill who was slowly tortured for weeks, and then chained to the prison tower for the vultures to feed on. He was still alive."
Tales of Saverill the Traitor are drilled into the memories of the Black Shields when they are pledges at the academy.