1) My first suggestion would be a blocking functionality for any update packets sent to the player. Often, you send fake equipment to a player, but you do not want any packets to expose the faked equipment until some condition is met. Therefore, I suggest an option like sendEquipmentChangeBlocking to send an equipment change and silently cancel any equipment updates until some end method is called.

2) Resetting any sent equipment: I currently cannot find any method that easily overwrites any fake equipment with the correct one. I.e. if you want to reveal the actual equipment, you need to manually send slot changes again, instead of calling a convenient method that sends out all the actual equipment of an entity.