Yes, weapons become outdated. Not only are offensive weapons far better now, but today's soldiers have access to ceramic body armor that can stop a 7.62x39mm round travelling extremely fast (900m/s and lower, depends on range). That will most definately stop an arrow, sword stroke or any other type of old-style weapon.
Also armored vehicles compound the modern advantage. Weapons and armor become outdated, there is no avoiding it and even though old weapons can still kill unarmored targets the speed, lethality, ease of manufacture, ease of training and quick reaction time of modern weaponry far surpasses old weapons. Theoretically a bowman could defeat a modern day rifleman, but he would need a certain degree of luck and suprise and armies need to be able to operate consistently.
I rambled a bit, sorry...
Bookmarks