This, I think, was 1/3rd of the first bike tool I ever owned. Purchased for me at around age 13, I've kept the same set of three tire irons quite a while. A couple years ago I lost one in some tall grass at a roadside tire change and the second one snapped on me recently, leaving one lone tire iron. This was a set of Dremefa tire levers from The Netherlands that came in the little red bracket with a rough patch on the side for tire patch installation. At the time, these were the only tire irons sold in bike shops. I found their maker on the web and they remain unchanged:
Photo from www.bobike.nl
If you look in the image at the top of the page, it seems like the crack initiated at one of the many grooves worn into the lever face by running the lever around the rim of a wheel I probably no longer own. Godspeed little tire iron.