Well it wont stop bleeding. Something a bot more drastic required I think to cauterize the wound somehow.
Least painful idea? I have some tint benz, zinc, friars balsam, but that would produce an impressive amount of pain.
What about a saline solution, just salt water?
Doctor Mick, Im looking at you mate.
Saline solution isn't salt water but use that to rinse if you need to. A procogulant dressing is what you need but I doubt you'll have one. You can make one but it involves some pretty involved chemistry. Friars isn't massively effective. If you have a styptic pencil for shaving cuts (styric acid and alum) it will stop but really sting