when one is using elemental attacks such as fire strike or primal strike, is it preferable to invest in spirit over cunning?
Both do have some physical damage too. Depending on what you want to focus on, you can go either way. Spirit increases the fire and lightning damage of those attacks, and cunning ups the physical damage. Pick your poison. Although you may not find either is a great investment, as you may find +damage% to be better.
I would go physique, elemental damage modifiers come in huge numbers a small amount the other stats wont make a big difference. Use them for meeting requirements