In earlier times Hoplites also had long swords, thats no reason that you aren't able to form a Phalanx. After all in the Phalanx the best weapon is a short dagger like the Spartans eventually used. Some Hoplites also used axes, would they also need more space?

The sword is a secondary weapon, when one drew it out it didn't mean that he went out of formation and went berserk at the front rank.


Also another unit for the density is the elite Phoenician-Lybian unit of Carthage (those with the axes on their shields).