I've almost finished reading the book series, and also played all games.

In the books, the fighting scenes were pretty detailled, with all combos (pirouette, counter attack, etc.) and all last and lethal mistakes their opponent did explained.

Thing is, I have zero clue what all attack patterns are, and looking at YouTube isn't helpful too, sadly.

Do you have any clips of in real live people, who practice swordsmanship, replicating those combos and maybe even fighting against each other?
I think those attack patterns are well known jargon for everyone fighting with swords.

In theory, would it be even possible to fight like Geralt or Ciri IRL, just thinking about how much a real sword weights and stuff?

I mean, for someone like a mutated witcher, that shouldn't be a problem at all, but how does that compare to someone like Ciri or Bonhart, who are excellent fighters too, but without the extra reflexes, strength and stuff? Especially regarding strength and endurance (men vs women)? Would women (just "women" in general, not necessary specific characters) even have a fair chance of winning a battle against a stronger opponent, usually men? Isnthat compensated by different fighting styles and just experience?

How would their fighting style be different than one of a witcher or a unskilled gang member?