I think it would be very cool if the Orders were expanded with lots of Order member missions with special or unique treasures upon completion. It’s an aspect of the game that is limited. The Orders are a cool part of the personal story but pretty much end there.
Maybe the Durmand Priory would investigate rumors of Vampires or ancient ruins filled with unique monsters and bosses leading to unique treasures only attainable by Order members who can complete the mission.