Its just occurred to me I've fucked my save somewhere because Jackenstein is fucking dead and I'm gonna have to replay chapter 4 and 5
Just edit your completion save using Tenna Editor.
Anyway, I've thought more about the twisted sword. In order to craft it, you need both the thorn ring and the "pure crystal," which we can only assume will be the item Seam gives us if you give him all five shadow crystals. Given that the shadow crystals contain the power of "lost dreams," perhaps the pure crystal is the inversion of that, meaning it contains the power to pursue a new dream. The thorn ring is an item that allows you to become more in touch with your inner desires, even the ugly ones you never wanted to accept. I don't think it's a tool that lets you control people,
because you can't stop Noelle from dragging you into the lake in the Weird Route no matter how hard you command her to stop. The twisted sword
doesn't kill enemies, and contains the "slay dark" ability from the black shard without listing it. Going off of stats, it's just a reskin of the black shard. Also, only Kris can use it. Everything is pointing towards its "trance" ability having a purpose, like it did for Noelle. Considering that the thorn ring's trance made Noelle more susceptible to giving in to her hidden desires, it's possible that the twisted sword doesn't necessarily bring out the worst in Kris, but instead focuses his desires toward finding a way out for everyone where nobody needs to get hurt. Of course, that's if we're considering the idea that Kris is working to sacrifice himself in service of protecting his hometown and fulfill the final act of the prophecy. Or, if we're considering the idea that the prophecy has already happened
"The Girl" being Dess and all this Roaring Knight shit is an attempt to undo the end of the prophecy
where The Girl gets banished to the Gaster Zone but that's even more baseless speculation, it'll allow Kris to find a new way to subvert the end and bring his friend back.