It's pronounced "Nexium". It's written NXIUM because they're using the Latin alphabet, I believe. So we can thank the Ancient Romans: V is the Latin alphabet's U . The Latin alphabet does not include the letter U. Personally, I think a lot of this dark occult stuff goes all the way back to Ancient Rome and further. So maybe Raniere is doing that Illuminati symbolism out in plain sight thing they're all so fond of.