To conflate the issue, you have items like Amulet of Fiery Fists, which says "You may not play a weapon on this check." I've always thought that was a little strange, because Amulet of Fiery Fists gets played in the step after the one where you would generally play a weapon.
I wonder if the intended effect is not to retroactively exclude a weapon from being played, but rather to exclude *itself* from being played when a weapon has already been played. Something like "Amulet of Fiery fists may not be played in a check where a weapon is played" would capture that idea.
But anyway, this does kinda relate to the current discussion, because if Amulet of Fiery Fists can retroactively prevent a weapon from being played during a check, it's not an unreasonable stretch to say that an item that allows you to play an additional item during a check could be used to grant itself as the additional item if another had already been played.