Found another picture of one. It belonged to an classifieds ad (no longer visible) on an Austrian website.

(Not my picture, copyright by whomever took it for that ad.)
The left side looks like the typical anvil of a striking/ slugging wrench. The right side looks like it’s just a hanging loop. I’m torn between which of the two sides is the actual business end. Never seen such a tool.
I would also say its finish is too rough to be some kind of (precision) gauge.
It could be some kind of “anvil”/ or stop.
I will go through a paper catalog and see if I can find something like this from one of my industrial suppliers.
I’d also suggest to ask Matador directly, would be interesting to know.
Kind regards,
Olli