there are no historically accurate slinging styles.
Nobody has the faintest idea what styles our ancestors used.
Logic would dictate that they slung with the same styles we use.
balearic/sidearm is one many people come up with on their own - I certainly did. So that's pretty much a given.
But everything else - just wild guesses based on some artistic poses on vases and the like.
Historians don't like applying logic or common sense to things our ancestors might have done,