As far as "practical" medieval weapons, I like my yard edger. It's a steel tubular handle with a small, thick, rectangular steel blade welded on, sort of like a flat shovel. If I sharpened the three edges and extended the handle to about 5 feet with a hickory tool handle, it would be a fearsome polearm. I'd probably add a dull spike to the butt of the pole, so I wouldn't have to set it down: I could just jam the spike into the ground. It would also give the little poleax a mean butt stroke.
The easiest medieval polearm to make is a classic flail, with a long handle and short piece of plumbing pipe attached to one end with a few links of chain. The beater hits like a sledge hammer, even after a short swing, and it whips around shield edges and upraised blocking arms. The problem is controlling it. A flail is a good way to be unpopular with your friends, unless you're very good with it.
A homemade "mace," with a heavy, short piece of steel plumbing pipe slipped over a heavy-duty handle and pinned or wedged in place like an ax head, would be more practical for most people than a machete, ax or sword. You could even put a short, thick spike in the business end. Used with a small- or medium-sized round shield, it would make engaging one or two walkers a pretty easy affair.