Lucy,
Amy,
Luke, and
Frank (although I included it on my list, too) aren't technically just nns.
Lucy is the legit. fem. form of
Lucius.
Amy is the English form of a French name.
Luke was, biblically, a name on its own.
Frank can refer to the Franks (though, to be fair, I more usually see it/consider it a nn for
Francis).
Just thought I'd say, since you pointed out similar things about
Sophie and
Liv /
Livia. :)
Shannon