@belnik, that doesn't work, it's still based of the main item, so you'll be editing all swords/daggers. If you know any programming, it's basically based on a class. That class is 'sword'. anything that's a sword is based on this class. With +xx% or whatever.
So king cailan's sword is based on the normal tier x sword.
As for editing the damage values, I don't make it really high (only change the base damage of swords to 27 or 28 making tier 7 swords have like 40 damage). Instead of relying solely on the weapon to kill, I raise the strength attribute of my characters. The Blightblood sword with a base damage of 27 has a max damage of 43.20. With a strength moddifier of 63, the max damage is 125.1 before you add in critical hits\back stabs or talents. Enemies will never has massive strength like that.
You can also increase your dexterity to reduce the chance of being hit and increase you constitution to increase your health. Remember, in an RPG like Dragon Age, there are many factors that determine combat.