I'm developing a DnD campaign with a focus on relative historical accuracy (in some areas). The setting is a time period that roughly mirrors technology and culture the late roman republic/ early empire.
So part of that is looking at weapons of the time. Looking at random internet sources, I see lots of things such as the gladius, doru, spatha, kopis, falcata, xiphos, which are all 1 handed weapons.
I guess my question is whether or not the small size of these weapons is related to the choice of the armies using them, or was there some technological limitation preventing them from producing longswords and such?
(Spears were the opposite of the weapon of choice for infantry in the Late Republic/Early Empire. In fact, the Romans, having initially used spears in the Early Republic, had almost entirely phased them out by the 1st century BCE in favor of the gladius+scutum combo. Virtually all the major civilizations that still used the Hellenistic style phalanges with spear/sarissa had been defeated by the Romans by the beginning of the Imperial period (Antiochos and Mithridates come to mind) ).
To OP: essentially our evidence for large, two-handed swords is non-existent in the period in question. That doesn't mean they didn't exist, but it tends to make it unlikely. It might be that there are metallurgical considerations/limitations in the ancient world (same would go for big axes), but that is well beyond my expertise. Your first impulse is probably right: that two-handed swords did not fit into the prevailing military thinking of the day.
A good litmus test is to look at the weapons of gladiators at the time. The Romans were very interested in "testing out" different combinations of armament against each other in the arena. Despite this, we have (to my knowledge) no literary or artistic examples of large swords being used in that context, though we have a large list of weapons we do hear about:
-gladius (typical short sword of the Romans) -arcus (bow) -fascina (trident) -hasta/doru (spear) -iaculum (throwing net) -lancea (a shorter spear) -pilum (a heavy throwing javelin) -pugio (dagger) -sica (either a dagger or a curved blade) -spatha (longer cavalry sword) -verutum (a Celtic strapped javelin)
the spatha was a longsword used by the romans just not two-handed :P. In ancient times we know that there are a few cultures that used two handed weapons. In Britannia we know that Caledonians, modern day Scots, used a longsword and small sheild From Tacitus:
"The Britons with equal steadiness and skill used their huge swords and small shields to avoid or to parry the missiles of our soldiers"
The Thracians are a culture that has used two handed weapons similar to the flax mentioned by others in the comment section it was called a Rhomphaia! as you can see it differs slightly from the flax used by dacians. The blade was either slightly curved or straight. In mordern greek the word Rhomphaia is translated as broad sword despite its pole arm type build.
Finally i think i should talk about the romans and why they didn't use any two handed weapons. it was not a technological limitation preventing them from doing so in fact they in the later years of the empire they switched over to a longer sword-the spatha. They did not use two handed swords simply because they could not use it in their formation. Not only that the implication of two handed swords would take away important formations like the testudo. If they would be in tight formations with these two handed swords they would not have much room to effectively use it since all you could really do is thrust.
Sources: Tacitus, Agricola: book 1 (36)
