Excellent work there! Somehow I missed this when you posted it - glad it's come up again, it's top-notch work.
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Etymologically, should Barbarians shave? Would they?

Well, the Greeks generally
didn't shave, so one possible explanation for 'barbarian' was that they did. The Bog Bodies from Denmark (homeland of the real Cimmerians according to the Romans) show that beards could be closely trimmed with scissors in the Iron Age.
Or, 'barbarian' might mean that they went "bar-bar-bar-bar" like this:

- ie, didn't speak Greek.
Or it might mean that they wore trousers. I really wish I had a source for this, but I can no longer remember where I heard it.