The ARR rework should've included a small extra step in the Company of Heroes chain pre-Titan where they won't let you continue until you equip your job stone. Have them frame it as saying that only a proven and exceptional adventurer could handle it, then a system message directing people to go back to their class trainer for the next quest. If a player already did it, great, they can continue right away; if not, they get reminded to go do it.