I believe I am at the final stage of the artifacts as Octavian says this will complete his collection. However..he refuses to take them. I have the required number and can select the option to turn them in, but they never get removed from my inventory. I can select it unlimited times but never get the reward.
Edit: Unrelated but I don't want to make a second topic. The raid in Beodricsworth is stuck on the map. I have 100% of wealth in the area but I can infinitely raid the area with no way to remove the map marker.