NEW IDEA
so a lot of the princes in the story start off with some op weapon like ahabs crosshairs or dirks unbreakable katana, and they just keep it the whole time (eridan gets the wand eventually but with kanaya's help). Cordyk could do with something like that for herself and i realized what would fit well:
the UNMAKER from doom 64 (also unimplemented weapon in the first doom and later brought back as the Unmakyr in eternal). its a secret weapon that gets stronger with demon keys and the original concept invvolved it doing a lot of damage to demons. maybe add in the soul cube as a power source for a general Doom centric weapon. plus i can reference the Doom weapons from the Artix games, powerful cursed weapons that grow in power by consuming souls, threatening to destroy their weilders
giant laser cannon go brrrrrrrrr