I have thought for a while that if I was ever in a life or death fight where I need to inflict as much damage as possible in order to survive, then biting fingers would be an option. I'm pretty certain I could at least inflict disabling damage on a finger if I got a proper chomp on it, and I periodically see openings for setting up a finger bite while grappling.A tiger will bit you before you get an arm bar on her. You don't wait for your opponent to get arm bar on you. You try to bite on his finger ASAP.
One guy tried to use his fingers to poke my teacher's eyes. My teacher used one hand to "redirect" his hand toward his mouth and bite off one of his opponent's fingers.
When your opponent tries to use his hands to hold on your arm, you can redirect his arm by using your other free arm and obtain his hand. When you use your free arm to pull your opponent's arm, either you can
- pull his hand near to your mouth, or
- pull your mouth toward his hand.
In other words, you have 2 arms and your opponent also has 2 arms, If your opponent can use 2 arms to get your 1 arm, your other free arm should can also be able to interrupt his arm bar.
Of course all these are theory. More testing will be needed.
It would have to be pretty desperate circumstances, though. You have to consider not only the potential health risks, but the possibility of serious legal consequences as well. Probably better to reserve that awareness for making sure my fingers don't get bitten.