This Hacking Knife from Footprint is a heavy duty knife you literally can beat on. It was intended to be used with a hammer to chip old putty out of window frames, but it has lots of other uses, one of those is as a Jointers Hack Knife. Cut wires, trim branches, split joints, notch out rough lumber...things you wouldn't dare do with a regular knife.
The tough, high carbon steel blade is hardened at the edge to stay sharp, while the back is left unhardened to stand up to hammer blows.
The blade tapers from 5/16" at the back to 7/32" at the cannel and is 4-1/2" long