This mod removes the Flaming Arrow UU from Korea and gives it to the Romans, renaming it Ballista. The skin is also changed so that the crew looks more Roman. The intention is to give Romans a boost in the classical age where historically they shined, and also in the game where they should indeed be a strong Nation.
Koreans instead revert to a catapult like everyone else in classical, but still get the heavy flaming arrow in Medieval, while the Romans revert to a Trebuchet in Medieval.
Installation: Make sure you have a mods directory in your games directory. Then unzip the mod files into this directory. The zip file should contain directory with a bunch of files including an info.xml file, and two subdirectories with altered unitrules.xml and unit_graphics.xml. There maybe an issue (read bug with the patch 3 modding method) that causes the skin to not work properly. So you may have to do it the old way (by copying the mod files into the actual game directory, and making a backup of the original)
The mod should then be selectable in your mod scroll down in your game setup, and if someone else has the mod they should also be able to play it in multiplayer. No guarantees the nations will be balanced though.