That said, Tom Shippey points out in Laughing Shall I Die that the Swedish vikings who went east and south to Constantinople and became the Rus originally called themselves vær-gengi, which means those who travel together in a business enterprise (piracy or trade). In Constantinople, this became the name of the emperor's Varangian Guard. It survived into modern Russian, though, as varyag = "trader, pedlar."
Not saying that Tolkien imagined the Variags of Khand to be piratical, mercantile, or mercenary. But as a people of the distant East, living at the southernmost extremity of the plains of Rhun, perhaps he pulled the name out of the recesses of his mind as one that just "sounded right."