Thanks for the information about the word barbarian in the ancient world. I had assumed it changed meaning over time, but as you point out, perhaps something of the old meaning still clung to the word.
Yes, I think our usual meaning of the word today is "uncivilized" or "primitive". But there is another meaning of "cruel or brutal". Civilized nations, in the sense of a highly developed society and culture, can commit brutal acts, such as the Japanese in China and the Philippines during WWII. That would qualify as barbarian. I don't have a copy of the EOD at home, but I will look up the word to see how it might have changed meaning when the word entered English. And of course words usually have more than one meaning which only the context can make clear.
One of the difficulties in reading old literature, for example the middle English of Chaucer, is that we tend to bring our modern understanding of a particular word to the work. So it takes time to understand old literature, and then perhaps you can only do your best without being absolutely certain that you have got it right. I would think that applies to Latin and ancient Greek as well.
As for Greeks and Romans hurling insults at their enemies, they probably did. But I doubt that using rhetoric to rouse the masses to hatred of the enemy was the primary reason to go to war for those ancients. Honor was probably a greater incentive to war, as well as desire for territory and booty.
The classical world was very different from us in some of its attitudes. One of the things that impressed me most in reading Plutarch was what he considered noble and ignoble.
Noble was a war leader who led his people to pillage, rape and enslavement of the enemy and became rich and powerful in the process.
Ignoble was a guy who ran a business that provided people what they wanted in exchange for their money. Successful businessmen often spent the second half of their lives pretending they had never been in business, and certainly their sons did the same.
IOW, he thought theft, if conducted in a military way, was far more honorable than business. He didn’t argue this point, he just took it for granted as one his audience would agree with, which they did.
It wasn't to rouse the masses to get into war, but to strengthen their support after war was going to be undertaken.