The assumption that the sword is or ever was a universal weapon is, in my opinion, false. The sword was a rich man's weapon and while that might have led to it being heavily featured in the modern day it does not make it a universal weapon. There can be only one universal weapon, one that is as old as the human desire to kill and lives on to this day, albeit in a heavily modified form. One that has been used in every war, on every continent, in every era by the richest of nobles and poorest of farmers alike. The spear. Cheap to produce, intuitive to use, versatile in application and every bit as deadly as the most beautiful sword, perhaps more so. If ever there was a universal weapon, the pointed stick is it.

EDIT: The cost of various weapons is discussed at length here by a great many contributor.