Apart from very extensive testing, knowing the enemies' stats, and the devs telling us outright the formulae, I don't think we'll find out how these stats work. I do have a few theories though:

1. Raw stats like int and str converts to derived stats like m.potency and att.power on some ratio or formula. This formula may or may not include your lvl as a multiplier.
2. Raw physical stats affects the effectiveness of your weapon in question (axe affected by str and bow by dex etc) in which case then, will end up affecting your damage but not your att.power because it simply adds a multiplier to your weapon's damage. If this is true, then it may also work for armors too where vit affects how much you gain from the item piece you're wearing.
3. Stats on gear affects your character differently than stats via levels or conversion traits. I doubt this is very likely though.

That the devs will be releasing the exact formulas for us to see seems unlikely to me. Maybe when parsers become a lot more common, and that enemy stats are more known then we'd be able to do some real testing.