Crafting Races
Much like real life, there’s no strict rules. Each race can operate more or less independently from the others, necessitating every discipline be present in some form.
Whilst it’s not hugely lore based, an easy assumption would probably be matching weapon/armour crafting with the professions that use the tools. For example, Huntsman are probably more likely to be Rangers or Engineers, as they use the products of the disciplines.
Just remember, it’s equally likely that adventurers wouldn’t have a crafting discipline at all, or just basic skills. Someone who devotes their life to crafting is more likely to produce better quality weapons then those who do it as a hobby, simply due to practice.
Hope that helps.