Why do people equate the double axe with Hephaistion specifically?
People mistakenly associate the double axe—properly called a labrys (pl. labryes), and pronounced LAB-rus—with Hephaistos. Ergo, it must be a symbol for Hephaistion.
This has all sorts of problems.
First, the labrys is also found in several civilizations adjacent to Greece, including both the bronze-age Minoans as well as the Thracians…who are just north of Macedonia, remember. In Minoan Crete it was only ever associated with FEMALE goddesses, and both the labyrinth of myth as well as Ariadne, “mistress of the labyrinth,” are connected to a female goddess, perhaps the Mistress of the Animals. So, there is some connection to hunting, but it’s primarily viewed as a religious symbol.
In Thrace, it belongs to Zalmoxis, the storm/thunder god. Zalmoxis was, additionally, the patron of the royal Odrysian house, not unlike Zeus as patron of the royal Macedonian house. So, it is a distinctly male (and royal) attribute in Thrace. There were Thracians in Alexander’s army, recall, and Sitalkes was one of ATG’s important generals, a friend to Koenos’s family (apparently). He was almost certainly an Odrysian prince.
If all we pay attention to is the AXE, we can make a far better case that the fellow hunting with Alexander is Sitalkes!
In Greece, the labrys pops up in mythical hunts, as for the Kaladonian Boar, so it can symbolize heroization not unlike showing people hunting or fighting naked. (We’re Big, Tough Heroes! We don’t need no stinkin’ armor!) Sometimes Zeus is shown with it, in place of the lightning bolt.
It is not especially associated with Hephaistos. He does have a double hammer, and I did spot a labrys on one pot in Berlin, but it’s highly specific there to the birth of Athena. One usage does NOT a motif make! Near as I can guess, the popular connection of Hephaistos with a labrys comes from a video game.
Er…
Pragmatically, it’s been theorized that the double-axe was used in hunting to deliver the final blow (coup-de-gras), which is exactly how it appears to be used in that mosaic.
All this explains why naming that figure Hephaistion because he’s holding a labrys is a bunch of hooey. As the Thracians were just north and already shared a goodly number of cultural connections, including some religion, I’m far more inclined to see the double-axe as a reference to Zalmoxis…assuming it references any god and isn’t exactly what it looks like there.
A hunting weapon.