Ah, where's Urnamma when you need him.... He could you tell quite a bit about katana's and how they are not superior to other swords.

Nevermind now this daydreaming: the OP wonders about the practice of overhand spear-fighting. We must keep in mind that there is a small but significant difference between martial arts and martial arts. The one used in combat is to be as effective as possible, and not getting yourself killed. Killing the guy opposing you is totally irrelevant, and besides the point (if you are not convinced, I sugges tot try and find statistics of how many soldiers actually aimed during WO2... nevermind now, how many soldiers actually shot...).

The other is more of an art form intent on -basically- showing off how well trained one is...

If we assume both to be the same, then there is also no sense in the Roman fighting techniques: I mean that scutum kinda takes up all the room to manoeuvre. However, since we do not assume this we can easily understand the combination: you hold the scutum frantically in front of you waiting until either the opponent stops stabbing at you or makes a mistake so you can stab at him...