The PIE root is debatable, as is much concerning a reconstructed language. The imagery of the parallel fingers and out-thrust spears is, however, clear.
As for barbarians, my ancestors were barbarians (being non-Greek) who practiced barbarism (being Borders reivers) and there is no shame to that. It is historical fact.
As a definition of a non-city based tribal society, the word will serve our purposes without importing any prejudicial (and therefore false) meaning.
As for fantasy stereotypes, I am afraid that we are as stuck with them as we are RW stereotypes. We have dragons, we have magic, we have monsters with vile natures, woodland dryads and subterranean dwarves. Stereotypes are a convenience, and even Greg uses them.