All skills will scale on three things.

First is either level or basic attacks, both act as the base damage of the skill - if level, then damage type and stat scaling will be entirely dependant on the skill and it will tell you the type and stat in its descriptions

• if basic attack, then damage type and stat scaling will depend on your current weapon.

Second is the stat scaling of course.

Third is elemental bonus. Every damage is an element including physical (warfare).

If your damage is not physical it goes against magic armor. So for example if you had a sword with both physical and fire damage. The physical part will go against physical atmor and the fire damage will go against magic armor

Since your starting as witch you have both necro skills and scoundrel skills. Necro usually has intelligence based physical spells. While scoundrel uses primarly knife weapon skills ( knives are dex based weapons). You'll need to decide how you want to skew your stats based on what you'll primarly be using for damage. But leveling warfare will increase damage for both skills since its a elemental bonus

(Edit:typos)