Until the melee / ranger characters start getting elemental damage weapons which is later in, I thought there was little to no synergy but around level 5 you start to see more.
As for Vitality damage its kind of crazy to ignore armors completely.
Rain of Blood does need to do Physical Armor damage for bleed check. Like chloroform does magic armor damage.
The Touch spells should do extra damage based on the weapon you are using.
