I understand that there are technically four rings for the fingers, and the fifth isn't really ring shaped, but I'm trying to go with a theme here, so bare with me.
Brass knuckles are an interesting weapon of choice in wrestling. So interesting in fact, some regions actually had Brass Knuckles Champions. Guys like Blackjack Mulligan, Rocky Johnson, and Black Bart all held the NWA Florida version.
I never saw any of these matches, as the title was retired in 1984, which was about the time I started watching wrestling. But I've seen plenty of villains use the knucks to their advantage.
Floyd "Money" Mayweather used them to knock out the Big Show at Wrestlemania 24. I was there for that, and thought the booking of the match and it's ending were actually pretty creative. I was skeptical of the match when it was first announced. I had imagined another catastrophe like the Big Show-Akebono Sumo match at Wrestlemania 21. At least at this one, Show was fully clothed.
My memories of the knuckles include Randy Savage using them to win the Intercontinental title from Tito Santana. But I'm pretty sure they were wrapped in something and not the exposed knucks we see today. Also, back in the World Class days, Gino Hernandez used them to beat faces like Kerry Von Erich among others. In fact, Gino was the Texas territory brass knuckles champion. Other legends like Fritz Von Erich, Abdullah the Butcher, and Bruiser Brody also wore that title. It was an active belt off and on since 1953, before the NWA changed it to the Texas hardcore title in 1999. That version only lasted a couple of years.
While there are no longer any brass knuckles champions, or at least none that I'm aware of, the weapon is still used today. We don't seem them a whole lot, but William Regal is probably the wrestler most synonymous with using the foreign object. Edge used them to beat John Cena at SummerSlam a few years back as well.
Running down our 12 Days of Christmas list (the whole point of this post)
A Red Rooster in a Wrestling Ring
2 Turtle Jobbers
3 French Canadians
4 Wooing Horsemen
5 Brass Rings