I've been lent an entrenching tool, which I've played with a bit. It seems to be the post-WWII
West German model, which has a shovel blade and a pick, and a good lock for them. It weighs 2.75lb, and if you sharpened the edges, it would be nasty to be hit with. You also can definitely hit people with the flat.
It's seriously unbalanced, with the centre of gravity at the handle edge of the shovel blade, but I don't have the experience to compare it with an axe or mace.
It's TL7, I reckon, for the neat lock and its spring. Making this before TL5 would be quite hard: its design is precise and needs to be fitted right.