I don't know what SHTF really means, but I know that one of my favorite Battalion Commanders was a Platoon Leader in Vietnam who's Company was over run. He was a huge fan of "standoff" with every weapon, but especially when out of ammo. More than any other unit I was in, we trained fighting with fixed bayonets and E Tools. He made us sharpen one side of our E-Tools. Caused a shxxstorm at CIF.
In defensive positions unit SOP was E-Tool lay extended within easy access. I would rather be armed with an E-Tool, than a knife in an all out fight especially if out numbered. I would always rather carry more ammo than a fighting knife on my belt/kit.
I agree with others and am in the Hatchet / Tomahawk fan club. At times I carried a full steel shank hatchet on my Ruck, I kept it slid behind / under an external pouch... it was not meant to be accessed quickly. Stowed to keep the Ruck streamlined. I used it more as a hammer then a chopper. Most everyone I know carried extra ammo on kit or belt. No big Rambo knives...little knives for cutting - not for fighting.
I really like those Hawks pictured above. Very nice. Mine was very "Old School"... East Wing blue handle.