How do Dragon Age: Origins Weapon Runes work with damage (fire ice and electric)

Question

While playing Origins, I started thinking about runes, and how they worked on weapons. For example, I have "Maric's Blade" with a +2 damage fire rune.

Does that damage come from the weapon's damage (I.E Normal Damage -2 damage +2 Fire Damage) or is it added on? (I.E Normal Damage + 2 Fire Damage)

Also, how does this fit in with spells such as frost weapons?

My "Maric's Blade" has fire rune, and is also Iced, is there any effect to that (such as canceling out), or do I just deal both Fire and Ice damage?

Answer 1

I recall that it's added damage of elemental type, which is supported here.

The Dragon Age Wiki states that multiple of the same type also stack. According to this thread, this applies even to damage of the same type, such as the Frost Weapons spell with frost runes.

So, for example, you could do two +2 frost, and frost weapon spell, and they would all add up on top of your normal weapon damage.