Weapon and spell crit scaling?

My doubt is, i have a stamina arcanist dps, i want to get my major savagery from potion, but I do use some magicka spells too, they will be affected too even tho I don't have major prophecy? Same for weapon and spell damage the higher is the scaling one?

Because i dont wanna run camo hunter and in banner i prefer to have minor heroism affix.

I saw on ninja pulls build he runs essence of weapon crit potion.

Thanks.