Uhh I am really not sure, but if I remember correctly from the days back then when I was still working on a Q3 mod, it is used for the first person weapon (change) animation. In other words: the weapon is attached to the weapon tag, and when you change the weapon the hand animation moves the tag so that the weapon…
I've searched for hard info on what the '*_hand.md3' file is in Quake3 (for example, "machinegun_hand.md3"), but all I can find is mere mention. I'm told that the game will use "shotgun_hand.md3" as a default if it doesn't find one for a custom weapon, so there's no reason why anyone would need to make one for a mod. BUT,…