A few things I want to make a note on.
First of all, I'd like to open by mentioning that all the historical treatises and recordings refer to as various types of swords like two-handed swords, longswords, bastard swords, hand-and-a-half swords as... you guessed it, swords. Whereas attempts at classifying swords came in the Victorian era. There were(and still are in museums as surviving examples) numerous swords that had their own specifications. A smith back then didn't use a graphical software to get the blueprint just right and used a pressure cutter and a power hammer to mass produce identical swords; no, they were sized and forged by a person. Naturally, it's almost guaranteed that no two swords were technically the same.
However, Ewart Oakeshott's classification of swords based on their developmental background(origin and time period) was a small step forward in studying of swords. Although it suffered from the Victorian idea common in sciences back then that all things given time naturally progress and become more complicated, and its classification is a bit too linear and rigid in nature, it still offered a clear, identifiable view into the development of swords throughout European medieval ages. That said, there are a few things I wanted to talk about in this mod's use of terms, particularly related to swords.
The greatsword entry was particularly interesting to me, since the mod tries to be a 14th to 15th century mod. I was looking at the raws, and noticed that minimum size to use one handed was a whooping 140,000 cube cm. Which is only 10,000 short of being as big as a gorilla. I thought to myself, 'Alright, that's fair.' But then I looked at the minimal size to use, and realized that it was set to 75,000. This is a problem in largely two factors.
The first is that due to a bug in DF's code right now, a creature's broadness and height modifier is not taken into account to determine who can use what equipment. Within the current version, it is only used for determining if it's used one handed or two handed. Which means even humans who as a species average at 70,000 cube cm
cannot use a greatsword in fortress mode regardless of their actual size. Under pervious versions this was not an issue given how they are not playable. Since the update a couple months back, we now get human mercenaries and citizens, so this is definitely an issue.
The second factor is that the definition of a greatsword in this sense. What I got out of the 75,000 size classification was that you designed it after
this. Unfortunately, this is the sort of a greatsword used in the 16th century. (Even the way it was used was quite far being swordlike, it was closer to being used as a thrusting pole weapon with double grip. But this is a different topic for another day.) However, according to Oakeshott's study, the weapons most commonly referred to as Espčes de Guerre, "Grete Swords", or more commonly as greatswords in the early 14th to early 15th century was Type XIII and XIIIa swords.
Here are examples of the swords. Type XIII had a shorter grip and shorter blade, while type XIIIa had a longer grip. They were only roughly as big as a late medieval longsword.
There rises a question: then, how do you justify separating a greatsword and a longsword? Concordantly, how do you define a bastard sword and a longsword? To answer all these, it'll take at least a few more forum posts that no one will muster the will to read, so I will keep it concise. The answer is you need to understand the historical context and the way the weapons were
used. Fortunately for us, we have a specific historical context, and all we have to do now is look up how they were used, and abide by that clear definition and work the mod around it. Here's what I propose you do:
Remove the bastard sword entry entirely: as it stands, it bridges the gap between an arming sword (which is a name given to one handed swords in the 15th century, excellent work there) and a longsword. However, the idea that bastard swords were two handed swords that could be used in one hand if necessary is largely a myth. The problem with that definition is that, as you've seen above, pretty much all sword barring really small ones could be used both one-handed and two-handed. (This is likely why all swords except arming swords were referred to as nondescript 'swords' back then) There is only one certain source iirc that specifically refers to a bastard sword as its own thing, and even then it was said to have earned it uniqueness to having a special type of blade (which wasn't explained in great detail). Needless to say, there is no surviving example of bastard swords. Change longsword's stat so that a portion(upper half?) of human population, not dwarves, can use it one handed.
With that, the greatsword's size and one-hand/two-hand requirements should be brought down to be
same as the longsword's new stat. Well, what is the difference between a longsword and a greatsword then? You might ask. In that specific historical setting, the difference would be in how the weapon was used. As you saw the Type XIIIa sword, you would have noticed that the point was rounded. It was not a thrusting sword. Remove the greatsword's thrusting attack, and either leave it's edge attack alone, or bring it down slightly to suit its new size better.
Of course, it's all a mere suggestion, but do have a look and decide yourself if realism is the paramount concern.