Eish! Iodine stings just as much as it did when I was a child and father used his vet medicine kit on daughter.
Inadvertent attempts at finger amputation by rusty wire not advised, but having iodine in a first aid kit is handy for those who do attempt fence mends without PPE (aka Personal Protective Equipment aka gloves).
What happened? A strand of ancient fence wire broke as I was tensioning it. Barehanded.