#4 is marked with a note that it does actual damage requiring healing afterwards, which is probably not especially helpful with breaking through Carissa Sevar's resistance, but maybe Keltham wants to do that, or maybe his own theory says it's helpful.
It's a self-heating disc with a single command word; speak once to adhere, then again to switch on heat, then again to switch off and loosen. It's mostly for cooking food under field conditions, but can also be used to apply steadily escalating pain to a person.
"I'm skipping #4 because I'm guessing it's not escalating fast enough, but this is kinda interesting even if you're a nonmasochistic dath ilani, if you just ended up in a world with magical healing. It's a self-heating disc that actually does burn whatever it's attached to, and Jacint's note says that to be a Security wizard you need to be able to keep Detect Magic running for 10 minutes with this stuck to your forearm. I'm definitely going to at least try that at some point, if I don't use up all my healing today, I expect I'll utterly fail to impress but I want to know."