The best defense is a good offense. This is because the defense abilities are lousy.
VitalityThe Vitality ability is useless. If you start out at level 1, with your +4% Vitality, that will amount to under 4 HP. The two Viscious Voidlings you meet near the start can do multiple attacks of 9 damage each. So that single point into Vitality will help you survive one half of one attack from the weakest enemy in the game.
No, that one point will not be any better 20 levels into the game either, because even though your scaling health gives that 4% more of a bang, it's still just 4%, and enemy damage will scale as well.
Vitality maxes out at 18%. You would need to dump in so many ability points into vitality that you'd sacrifice your combat prowess.
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Aerotheurge:
+Affects every type of Magic Damage
-Only affects the damage done to Magic Armour, which many enemies don't have at all
-Doesn't affect damage done to vitality, and enemies have much more vitality than Magic Armour
-Encourages bad behavior of having Magic users target enemies with Magic Armour
This ability appears good at first glance, but is a bad choice to invest in as it only buffs the portion of the damage hitting Magic Armour. Have your physical attacks target mages, and skip this very under-performing Skill.
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Warfare:
+Affects every type of Physical Damage
-Only affects the damage done to Physical Armour, which some enemies don't have at all
-Doesn't affect damage done to vitality, and enemies have much more vitality than Physical Armour
-Encourages bad behavior of having physical attacks target enemies with Physical Armour
I'm going to gently contest your dismissal of Warfare and Aerothurge as being bad for their bonuses applying to physical and magical armor. It will not always be the case that you will face enemies which only have physical armor and no magical armor, or vice versa. There are times when you will be facing enemies with both.
Plus, even in the instances where there are enemies with only one type, after you successfully kill them, there will likely still be enemies remaining which have armor, and then the bonuses will matter.
Plus sometimes it might not always be possible or feasible to go for an enemy with no armour resistant to your damage type due to geography or surfaces or the amount of AP you have, and targeting an enemy which is close but has armor might be the better approach than walking into the middle of an enemy group to try and reach an enemy which has none.
