There was actually a Fist Weapon that was removed from Tibia!
Apparently, the name was Knuckles (but I cannot confirm).
I could only find a SINGLE screenshot proving it. It is a really old one that I got from a Reddit topic. You can check the item right below the Knight Legs in this screenshot:
A big thanks to the user Verkon from Reddit for mentioning it! He also claims that this was most likely a 4.0 or 5.0 screenshot. You can find the post in this thread by Guarilonio:
As a second note, a item that probably was remnant from when Fist Fighting had something else was the Power Ring. You can read mopre about the history in this thread by Urinecakes from Reddit:
However, I cannot confirm if the Power Ring being realted to Fist Fighiting is that old, since I cannot find when Cipsoft started to make rings grant you powers. Bright Sword Quest is a old quest so it might be that the ring was just for the quest back when Knuckles apparently existed, as I could research about on Tibia Wiki page:
Just to mention something important, we currently have a item in game that looks like a fist weapon but it is actually a club weapon! It is the Pair of Iron Fists!
You see a pair of iron fists (Atk:45, Def:17)
It can only be wielded properly by knights of level 50 or higher.
It weighs 45.00 oz.