Archmage is probably the title most mages, including me, want. I however hope it will be gated behind a long classhall/artifact chain so that not every alt mage will be running around with the title.
It make sense that the title refer/refered to the Tirisgarde though since we are meant to be its champion/leader. Maybe something like <Archmage "name" of the Tirisgarde> to really push how important we are with the option to turn on/off either the start or the end of the title. Wishful thinking but we all know that the more/longer titles you got the more important you are.