When a card is treated as a different type of card, game rules and special abilities that affect either its natural card type or the card type that it is being treated as can affect it. For example, once a game rule is performed on the Covenant or Curse that is a Artifact- or Enhancement-specific (i.e., putting it in the Artifact pile or playing it on a character in battle) it becomes "treated as" an artifact or enhancement (whichever one the game rule was unique to). So after a covenant or curse is played in battle it can be targeted by a special ability that targets enhancements and after a covenant or curse is placed into an artifact pile it can be targeted by a special ability that targets artifacts.