...They where abandoned because it was easier to "shoot someone dead" someone before they could make use [them]...
...The modern age has the stopping power, but your not going to beat the sheer collateral damage of the dark ages....
...They will be parrying and dodging, moving out of the way...
I have no desire to see UFO:AI turned into a Might-and-Magic game (they almost always had some kind of super tech hiding somewhere.)
We'll both romanticizing it, but I think you more so, the Gladius wasn't designed for a sword fight, parrying or anything else. It was a glorified precursor to the bayonet? It wasn't a sword in the classical sense of the word. You stab with it, that was about it. If you got in a RPG style sword fight with a Gladius, outside another short sword, you're dead or very good.
Outside spear's it's most famous use, that I know of, was a phalanx. A line of shielded soldier would make "lighting fast" thrust from
behind the shield at the enemy*. The target didn't have much of a recourse to party or dodge, in a pure infantry battle your options where:
1.Out flank the phalanx.
2.Get out of the way, run.
3.Die(Stand your ground in any way shape or form. A second phalanx just means they die as well).
I'm no expert on Roman history, but it the day's equivalent of the SMG. We use SMG instead of short swords today because the SMG can do more total damage at a longer range, not because the chucks of iron or steel was not more deadly.
Just in case you are squeamish, again, something you may not want to read, sorry.*The Gladius was tailor made to be used almost exclusively as a tool to make upward thrusts from the belly into the chest cavity. That's it. Thinking about it, it was nothing more then a glorified bayonet.
Edit, visual picture:
Did you ever see Lord of the Rings: The Two Towers? At one point during the siege of helm's deep the Uruk-hai(the big orcs) where marching up the ramp to batter the front gate in? Remember how they had their shields positioned? Not a perfect example, but there is a visual example of how a phalanx works. (I know they got flanked by the archers on the wall.)
Why am I in awe of melee weapons? You unload a few clips of a automatic rifle into someone, even if you can't aim that well, it's a safe bet their going to be dead. Given the choice of that or a sword, I'd pick the rifle; However, we turn a corner at the same, and one of us has a short sword, the other
will be dead.