This is one of the few modern names I like because a long time ago, I was looking to make up a feminine version of the name Xavier and I made up Xaviah, not knowing that this name or similar names even existed. Then later, I dropped the h from her name. I think it's a good name for a character, but not necessarily for a child.
I love this name! I first heard it in the song by The Submarines (as listed above), and thought the sound was highly melodic, even thought the name started with an (ordinarily harsh) 'x'. It's a modern name that is still quite versatile. I can actually see it on a little girl, and on a full-grown woman.
This is definitely not pronounced "eg-ZAY-vee-ah," because it doesn't start with "E." A name pronounced like that would be spelled "Exavia." (Would that mean "out of Xavia?" Weird.) If that were a correct pronunciation, I could pronounce "xylophone" as "eg-ZAI-lo-fone" or "ek-ZAI-lo-fone." An "X" pronounced as "ex" at the beginning of a word has a hyphen between it and the word, as in "X-ray." The "X" there means unknown, as in a mathematical variable. But it would be confusing and nonsensical to put variables in people's names (also, what kind of meaning is "unknown avia"?) and thus this name is not to be spelled "X-Avia." PLEASE pronounce it as "ZAY-ve-ah." Thanks!