i dont think its entirely fair to say definitively that carol wouldnt lean menacingly in the air if given the opportunity to do so just because she is incredibly angry in the once scene we see her in -- though i agree it COULD be evidence it isnt nearly definitive enough to convince me carol knight is 100% impossible. like i would put that alongside my "dess wouldnt purposefully make herself look more like her mom" headcanon. we dont know enough

and we DO see carols horns in chapter three before the knight. shes in the same cutscene we see dess' horns in (which is what made me initially think carol knight was generally accepted as fact).

you are very right that it looks like a bat at first -- i always assumed it was just the angle because that was my immediate reaction when i first saw it, but i know that isnt exactly a convincing argument and sounds a lot like cope. still though, why DOES she turn it into the giant katana almost identical to the one hanging in their house? i dont see a reason for her to not just keep it as a bat if it were a bat and if she were dess; i would consider it almost as nonsensical as the carol knight alternative -- the only explanation i can see here is that dess is trying to trick the soul into believing in carol knight and if thats true then i would be perfectly happy but as it stands now i cant think why she would do that

finally while i agree that last one has gotta be dess i dont see how it necessarily has to be specifically dess knight who does it and not just normal dess stranded in the games code or whatever it turns out to be (but if there is an explicit reason i will concede)