No doubt the idea arose from the Latin, where for instance
Victor (m) becomes Victrix (f). But that argument breaks down, firstly because
Vercingetorix never was a Latin name - just the
Romans' best shot at spelling a Gaulish name, and secondly because the original bearer of the name that we know about must have been a formidable soldier, because he gave
Julius Caesar a very hard time indeed and won his respect.
So I see
Vercingetorix as a girl name as a badge of her parents' ignorance. The fact that I don't like the nns
Tory and
Trixie doesn't help.