Relics should always be the best weapon for their level range, and if the level cap is raised there should be quests to increase the power of the relics. Although with this, to prevent everyone from eventually having the same weapon, I think there should be graphical changes to them or even replacing the relic with stronger relics of a new name. Like Curtana going +1 and +2 and +3 and the at level 70 turning into Excalibur or something. Just an example.

Maybe add some particle effects to the relics after they are upgraded to 55 or 60 and weaponskills. I hated in FF11 seeing the same graphic for 7 years.