To those who say that the Order didn't gain anything
To those who say that the Order didn't gain anything:
Tarquin lost his axe before he teleported out. What if his name is written on it ("To Tarquin with love from [name of wife]"). Then they will know who is behind the mask.
Does Tarquin have any weakness? What could be a potential weakness is that he cares a lot about Elan. That could be the beginning of a new plan.