I think potions (and to a lesser extent food), the Bless and Magical Might spells (never tried either) are it for temporary buffs. The passive Augment Damage skill will do the obvious, and Stun is quite helpful when maxed. At least in the disk version of the game, mixing any two of the passive Stun skill, Stun on a weapon or Frost on a weapon could result in occasional opponents hanging in mid death animation, though there are a couple ways to force it to finish (so they give experience and possibly drop loot).
I didn't bother with the passive melee damage bonus skills; they need to be almost maxed to have a significant chance of being triggered, but by the time I was a high enough level to do so I didn't need the extra help (higher level opponents start having higher resistances, as well).
Aura of Guarding and Spellshield absorb a certain amount of physical and magical damage, respectively. I maxed both with purchased skill books, and they were helpful in the middle of the game (I didn't try them until they were level 4 or 5, so they probably could have helped earlier). Spellshield is particularly helpful when dealing with opponents or traps that use poison, as the damage comes off the shield, and you don't jerk around with reduced offensive and defensive capabilities.
Survivor's Instinct is helpful to automatically top off your hit points when you return to base to stash loot or visit merchants, but it does not heal fast enough to make much of a difference during combat.
ARIC'S WARRIOR GUIDE (based on the disk version; some of the spells/skills were modified a bit in the download version)
