Depends on what kind of zombie you’re working with. There’s so many basic versions now that it’s impossible to be generalized in weapon choice. Ever just the split between slow and fast zombies makes it difficult.

But, if you go with the classic slow zombie ala night of the living dead, you want something like a machete in size and weight. Mobility matters in that kind of fiction, and when you start doing weapons training (regardless of origin), lighter weapons always let you move the most. Single handed weapons are almost always lighter.

Something like a katana is better reach, but you sacrifice a free hand for a bite shield with that type of zombie something to shove in their face at a bare minimum.

Baseball bats are vastly exaggerated in the damage they can do with a single hit. Living people can be killed like that because our brains are more vulnerable to coup/contracoup injury and the affects of skull traced fracture. Zombies don’t get edema or the other problems from superficial TBI, you gotta get the brain stem at least damaged. Even with Walking Dead scenarios where the zombies don’t follow human physiology, the one hit kills by a bat are bullshit. It just doesn’t work like that outside of the hand waving of fiction. And, imo, zombie apocalypse thought experiments like this should have a basis in at least semi-realistic scenarios, otherwise I’m casting magic missile every time.

So, stuff like axes and maces that would be great in war based on history fail vs zombies because you can’t reliably destroy the parts of the brain that keep zombies moving in non-magic scenarios. Not in one hit, anyway. And if you’ve ever chopped wood, you know that tool axes are not something you can swing from the “hip” with. You use gravity and muscle to make them effective. A hatchet would be better than a wood axe because at least you can kinda chop sideways with one and have a chance at a zombie finish in one hit.

Plus, if you’ve done weapon training in more than one type (even at a casual level), the bigger the weapon, the faster you run out of steam. You do a dozen reps of the same technique in iaido, and you’re feeling it. Same with kendo, and shinai are lighter than even the aluminum versions a lot of iaidoka use.

If you’re on the run, fighting zombies up close, they don’t run out of gas, but we will. And nobody has the gas to both run and swing a fire axe every time a zombie gets close without eventually exhausting themselves, and that’s a bad scenario.

You gotta remember, most swords and such weren’t used for sustained fighting historically. Infantry carried spears and polearms, and there was still attrition due to fatigue. But those aren’t good for skirmishes (which is the only smart choice vs zombies if you’re alone or in small groups). Spears work, but you’d be better off with shorter versions like the zulu are famous for. They take precision for zombies though, and that’s not ideal.

Nah, you want one handed blades with just enough weight to damage or destroy the brain stem. Nothing bigger than a machete, though you’d ideally want something with a better steel choice and less proclivity to deformation than the typical machete. You’d want to invest in a good one of those.

And, if we go after fast zombies ala resident evil, the problem gets compounded. You don’t have time for precision, but hits that slow them are useful, so you’re having to hit more often per zombie. And you’ll be doing it on the move with higher speed because you can’t just stand there and step from zombie to zombie without being swarmed hard.

Even in training with “practice” weapons, two opponents is a nightmare. Three becomes a very dangerous situation no matter how long you’ve trained. I’ve seen pretty skilled dudes with advanced training get negated by numbers of much lower ranked partners. Three is about where anyone ends up in a position where survival would be difficult if things were real

Zombies roll deep. Dozens, hundreds of the fuckers depending on the writer/scenario.