Preety sure it wasn't on the list. Was it?
Correct. "Volatile" is not a virtue in any case of the word.
Volatility. And I'm not sure exactly how you're defining virtues. If you want to be the most specific, cardinal virtues include Prudence, Justice, Temperance, and Courage. Sometimes, Chastity, Charity, Diligence, Patience, Kindness, and Humility are considered the Seven "heavenly" virtues, to oppose the seven deadly sins. Faith, Hope, and Charity are all also virtues of a different kind. I'm wondering how this list was generated, and more specifically, whether or not it was made by somebody who really understands virtues. Volatility is just as virtuous as Readiness, Gratitude, Divinity, Caution, or any of the other accepted names out there. That being said, if there's actually any reason behinds the words in this list, that would be enough for a theme, in which case you would be right and "Volatility" would be unbefitting as a shard.