Assuming the following cases for acquiring artifacts:
A. Open chest / Perform duty / Win sigil fight
B. Open an artifact item on the map (e.g. the swords in the heaven maps)
It seems that (B) artifacts are much more powerful compared to (A) (their base stats and/or amount of extra slots)
However (A) artifacts are much harder to find compared to (B), on a map that has (B) artifact nodes there might be an average of 5 of them.
I believe that (A) cases should reward better artifacts and probably the quality might not be the same among the various cases.
A possible issue for the current situation might be that power balance does not feed into the quality of (A) artifacts but does on (B). Or I am just mistaken