…Ick. And I wrote it.
Wirestrictors
Generally speaking, necromancers prefer to bind dead human souls into items, instead of animals; mostly because it’s easier to suppress a human soul’s innate intelligence and ability to understand language than it is to boost an animal’s. In fact, it’s largely impossible to do that with animal souls at all. What you rip out of the body is what you get, and if what you got was something not capable of doing anything elaborate, you had better stick with simple.
Wirestrictors are pretty simple. Take one constrictor snake, rip out the soul, then shove it into a long, strong metal wire (showing no care in either the ripping or shoving: you want the snake soul upset). Then set a secondary spell that will render the snake soul ‘unconscious’ until a pre-chosen triggering mechanism is activated. Coat the wire in something that will hide the discoloration and reek of wrongness. Attach the ends to a brooch or gem or whatnot (not too strongly).