Much like the axe in terms of dynamics, many of the same tactics used for the axe can be applied here. The biggest difference is that an axe cleaves things, anda hammer smashes things. Any zombie body part you hit with it, might possibly cease to be a solid, singular object. However, it is a very heavy weapon, with most examples weighing in at between ten and twenty pounds. Unless you are built like an ’80s action star, you will probably be tired out by carrying this weapon. It can easily keep a zombie at bay, as even a blow that doesn’t have the power to smash bones would still knock the zombie back or on to it’s ass.
The shovel is definitely a weapon of opportunity, probably more useful for burying stiffs than killing them. However, in the hands of a good user, it could serve some purpose. Shovels with longer shafts can be swung, much like a dull axe. However, shovels are heavy, and over-swing is an issue. The blade could be used as a small, improvised shield, useful when your opponent swings back. The blade is not sharp, but getting whacked with it would stall a zombie for sure. Use it until you find something more suitable. There are smaller shovels that can be used in much the same way as a hatchet, to the point where the US Army trains its troops in its combat use. Military spades are known as entrenching tools, or E-tools. Still, use it until you find something better.
There isn’t much to be said about the pick-axe that hasn’t already been mentioned. Similar to an ax in design, with the exception of a spiked head on one side, and a flat chisel on the other. It would be used for impaling an opponent. As a plus however, the elongated head could be use to block and counter enemy swings. Obvious drawbacks are over-swing, and getting the pick stuck into objects. Also fairly unwieldy for tight places. Overall, not a bad weapon of choice, that would be fairly common in garden supply shops, tool retailers, etc.
The pipe/monkey wrench may not be your first choice for a weapon, but this hunk of steel is quite effective in close-quarters combat. If used correctly, it has the capability to break bone and crush skull with generally less effort, making it an effective bludgeon. Its variety in sizes ranging from smaller single-hand versions, to larger sledge-hammer sized versions make it one of the more difficult tools to judge. Its uses as a weapon vary as much as it does in size.
As good a weapon as the pipe/monkey wrench is, its practical applications must not be overlooked. It can be used in the place of any of a large collection of wrenches, loosening nuts, bolts, and pipes of a wide variety. This makes it an ideal tool when salvaging parts from machinery and certain kinds of constructions.
Overall, the pipe wrench is very useful, and you might want to hold onto it even if you don’t plan to use it for zombie killing.