Consider this: the zweihander weighs seven pounds. The display version is ten pounds. If you can lift a backpack crammed with textbooks, you can lift a zweihander. House cats weigh more than a sword.
The issue with the zweihander is length, not weight. It is not a heavy sword. No swords are actually all that heavy, because weight defeats the purpose of the weapon. The heavier it is, then the faster your arms wear out and grow tired. This is a terrible, terrible thing.
Combat is highly frenetic. An easy comparison is sprinting, and it’s not just a regular sprint but wind sprints. You gotta go, go, go. You need to be able to move. So, a heavy weapon is detrimental to the goal of being able to fight as long as possible. Especially when that weapon is designed to give you an edge in reach, and counter pole arms. You want to be able to swing the weapon around for long periods of time because if you wear out first, you’re dead.
Endurance, not strength, is the great necessity for any warrior. So, everything your PE teacher punished you with is what you’re looking for (except dialed to eleven). Once you understand fighting is about going for as long as possible between energetic bursts, combat starts to make more sense. This is also why most action movies feature the pressure cooker, the slow grind down of the protagonist by giving them little to no rest between fights as they accumulate more injuries.
So, when people say strength in regards to combat, they don’t usually mean physical strength in what you can lift. They mean how long you can go, what you can endure before finally keeling over. This gets misinterpreted, mixed in with the confusion by historians about parade swords (which were incredibly heavy and often the only surviving weapons) and we get the beefcake barbarian.
Like all swords, and even shields, the zweihander is awkward to use if you don’t know how to wield it or have never held one before. This has to do with its balance point. Swords feel heavier than they actually are when we hold them because the balance is midway up the blade and that strains the wrist, which strains the arm, and causes the whole thing to tilt forward. Sometimes, the sword even gets dropped. You’ve got to learn how to account for it.
When you’re looking at actual combat considerations on weight, that’s in the armor. Armor is comparatively heavy, the warrior has to get used to carrying around fifteen to twenty or so pounds, or more depending on what gear they’re lugging with them between battles. So, if you’ve got a character going into battle without plate then they’re not going to have those weight considerations. Even if they are, the point of training is to build your body up to be able to handle it.
At the end of the day, its important to remember that, historically, large scale combat has been about being able to get the most bodies on the field as possible. You ran the gamut between trained warriors and farmers yanked off their fields with a hastily cludged together pole arm thrust into their hands. There are plenty of people who went into battle with no freakin’ clue what they were doing. The concept of a military as we know it today is a mostly modern invention.
The mystique of the knight and others like them came with their training, which is… they had some. Whatever they’d have liked us to think, there was nothing different about them compared to the farmers except the money, the (sometime) power, the time, and the “luck” of their birth. In the end, it’s less about what humans can or can’t do but what society corrals them from learning. It’s easier to control your population when only the powerful have access to weapons, educations, and castles.
So, yeah, a woman can use a zweihander if she trains on the zweihander. It also won’t be her only weapon, mostly because one never knows when they’ll have to fight indoors. (That’s a joke, HEMA peeps. I know half-holds are a thing, and it’s not a katana so it can strike straight.)