If you clamped those on a bull, seems like the jaws would cause more pain than compliance due to the ends not being rounded like more bull leads.
Judging by the age of these, they are pre-rounded ends - smith made - it is the (increase in) pain that made the animal compliant - animal welfare was not a priority at that time...
So, how do you know the age of these? Were they carbon-dated? I can make a set to look just like them, bury them in some adicic soil for a while, dig them up and brush them off to make them look the same.
Who wants a bull bleeding from the nose, anyway, regardless of time frame? Pain compliance only works for a short time, too much and the animal (or person, in my experience) gets a rush of adrenaline that pushed them right through the pain. I was taught pain-compliance for humans at my training academy some years ago. The idea is to drop the level of pain, after compliance is achieved, not permanently injure the subject.
I will agree they were hand forged.
I still say hoof tester.