Some effects in the game can temporarily or permanently downgrade your Weapon. If an effect is temporary, leave the Weapon Sheet to the side for the noted duration. If it is permanent, return the Weapon Sheet to the Weapon deck. In both cases your previous Weapon becomes your new current Weapon. (You can never lose your Bare Hands Weapon, however.)
You may voluntarily downgrade a Weapon as a General Action. This downgrade is permanent.
This does not cost any resources but consumes your turn during combat as a General Action.