I've tracked down the problem to def
csvquote, specifically the code
str[/\s$/] which
I interpret to mean "a space then the end of a line". Removing this code will prevent quote marks being put around the BattleBack phrase.
For some reason this code always returns true, even if there are no spaces in the phrase. If the meaning I came up with is correct, I can't think of any instance where it would be useful, so I don't think removing it would adversely affect anything.
Please let me know if you find any problems caused by removing this particular bit of code. It will also be applied to the next release of Essentials, so hopefully any problems will appear soon because of the (hopefully) many users.