May be this is intentional, but it seems more like the chat text when playing Impetuous Heal is some remains of the league: Blackhammer heals all on their own. (Or something like that) It makes it impossible to see in the chat which player has played the card.
Blackhammer is the item that it comes from, and the Impetuous action is supposed to be the item doing it on its own. It's like the item is its own character, so the text log announces that Blackhammer is doing this action for flavor reasons. You do fight against those items at some point in the campaign. Since it's a trait, you know which player did it last, but not necessarily which figure played the card.
Is this Artifact Anarchy? The other hammer in the league has a different name, so you should be able to tell with that.
I believe this might be refering to impetuous heal in quick draw in which obernoob point would make sense - it is kind of bad if you can't check from battle log which of your opponent drafted impetuous x.
