I think punching with rings is just going to hurt your fingers. I heard of turning rings around and using open-handed "slaps" with the ring on the inside of hand.

Now if you mean those weighted rings that go on the arms in some kung fu styles, I'm pretty sure they are just for training.

The purposeful use of a ring as a weapon will open anyone for criminal charges under concealed weapons.

Using a ring to strike effectively, not just punching, takes specific training and continual reinforcement, as you would be striking specific points on an attacker for greater effect. Someone buying a ring and thinking this gives them the ability to defend themself instantly is making a very poor choice. They're more likely to get a better return bying a kobutan or carrying a strong pen and learning how to use it, than thinking a ring is the answer.

While there are a very few groups that have the potential of using ring striking, this is not a beginner option.

In fact use of any hand held weapon in most cases should be secondary to strong empty hand training (though the escrima arts are an exception to that answer).

Of course the most powerful hand held weapon any of us are likely to touch is a car, and I would never advocate using that either.

The name you are looking for is "Kakute" and there is a post in this forum about it.

Dang... that was definitely the biggest necropost I've ever witnessed!

I am merely going through posts and saying what I have to say. Expect more.

I think this guy might be talking about the huge iron/brass rings worn on the arms in CMA such as Hung Gar, as opposed to the small rings worn on fingers