Drop or Discard in Mansion of Madness?
I interpret that card as "Discard means discard. Place in the discard pile."

The action is something that players can do to leave equipment cached for each other.

The mythos card is an act of aggression carried out by the Keeper. It probably costs Threat. There is also zero support in the fiction for a weapon becoming reloaded by being dropped.

EDIT: OK. So, I played Mansions last night for the first time in a while, and came up with this card. It's clearly Discard on the Mythos card and Drop in the Investigator action list. There's no confusion here at all, no interpretation necessary.