then it is unrealistic to EB to see the troops with long sword (like solduros, calawre, also all axes or falx units) fighting in a dense formation.
they should fight with a few meters away so as not to injure each other.

I read somewhere that the legions of the first quarter century BC fought in open formations to ensure that soldiers are injured among them. But with major discipline and training, after 3 centuries, have been carried out the first dense formations that were truly unassailable (even the cavalry, which at that time was weak).

Also oval shields (suitable for the long sword) reported legions back 500 years.
Which ridiculous shields wall you want to do with oval shields?
Oval shield (adopted ater Costantino's reform) has a value only in 1 vs 1 combat.

In the fourth century a legion was not more powerful than a barbarian's horde because all fought in the same way.

then i ask again: can the long sword has changed the fate of the empire?