most effective melee weapon?

[econ21]

I voted under-arm spear, only to find out that I chose the least popular option. (It's just you and me, so far, Simmetrical.) I was thinking here of infantry weapons and ones to be used in massed formations (not single combat).

The main reason I chose the spear is is that if we look at the popularity of weapons in the pre-gunpowder age, the spear just predominates in virtually every era. Only in the era of full plate is it superceded by its evolutions - the pike and the halberd. Even in the era of the gun, the bayonet effectively makes a firearm into a spear. You could say that is just a function of its low cost, but I don't buy that as many warriors would have a sword or something as a secondary weapon. Even in the musket age, I think nations could have afforded swords as well as muskets if the sword was truly better than the bayonet (spear). No, I infer the reason that the spear predominates is that warriors and soldiers - or the people who equipped them - believed it to be the most effective melee weapon.

The advantages of the spear are:
(1) Stand-off ability - perhaps particularly useful against cavalry.
(2) Reach.
(3) Penetration (when thrust with two hands).
(4) Probably requires less training to be effective than some other melee weapons.
(5) Can be effectively used in relatively dense formations.

Now, there are some exceptions to my argument that the spear predominated. The Romans, with their gladius are the most puzzling. [I confess I voted without spotting the option of the pike, but essentially the pike is just a spear taken to its logical extremes - maximising some benefits at the cost of inflexibility and a higher requirement of training.] From the success of the Romans, it seems clear that the spear was not that superior to the gladius or the legions would have been the ones slaughtered, rather than doing the slaughtering. But the fact remains that even the Romans moved away from sword-armed infantry and not many later armies followed their approach.