The idea of the legion might come from Imperial Rome, but the Imperials are very clearly stylistically based on the medieval "Byzantine" empire, which most certainly did not have extreme standardization. Byzantine infantrymen used both axes and maces alongside spatha-derived swords and, later, sabers and saber-like swords.
Iirc, when they had to rework their engine (again) they discovered that the system didn't work. But don't quote me on that.
Played beta as well. Never had any issue with cav so long as I put my unit in square. Archers though? Wew. It's like armor is made of cardboard.
Spears exist for a reason.