duplicator has nothing to do with subweapons. you're talking about the single-use items you get, which aren't quite the same thing.
the sotn spell system is quite a bit better than portraits. there is nothing interesting, engaging or satisfying about simply holding up+ attack for a period of time. it, like everything else in the game, is incredibly shallow and superficial; any kind of satisfaction is ultimately weak and forgotten moments afterward. the entire game is designed towards an ADD "constant tiny miniscule rewards" mentality.
in sotn, successfully pulling off a spell was satisfying; it wasn't always easy, it was something that had to be earned and its effect was generally interesting (rather than falling under two primary categories: temporary stat boost, shoot something directly ahead of you). in addition, it was something that was always with you; there was an element of uncovering, of discovery, in the spell system. this adds another level of satisfaction and depth on repeat plays: you now likely have the whole arsenal of spells in your head, capable of being utilized at your whim rather than not figuring out it was there or not knowing how to do them until quite a bit later in the game.
further, it shouldn't matter what the intent of mechanics in portrait were; they were failures. trying to fix something doesn't mean its going to be better, its more than possible for these attempts to result in failure.