I tried to search for the answer, couldn't find anyone asking the same question.
Basically, does it matter which dagger the rune is on when it comes to getting the bonus from the rune?
For instance, I know that when you use Hidden Blades, the damage comes from your 'main hand' dagger, since it is not a 'two dagger' attack like Twin Fangs. (that hits once for each dagger) But when it comes to the bonus rune damage, do you only get that damage when using that weapon, or is it applied more globally like Attack % and % Critical Damage Bonus?
Basically I just want to know that if I hit a Dragon with Hidden Blades and the Superb Dragon-Slaying Rune is on my off-hand weapon, will I still get the bonus damage? Or does the rune just augment the base damage of the weapon it is applied to?
Yes and kinda no and sadly, no.
For auto-attacks, it kind of doesn't matter, although the mainhand gets a slight damage bonus, while the offhand gets a slight damage penalty, regardless of runes.
In terms of abilities, only the mainhand dagger base damage is applied (but see below). Doesn't matter which ability, Hidden Blades, Twin Fangs, Toxic Cloud, anything that does damage.
For your specific question about HB using the rune, runes only apply to auto-attacks and KE Sprit Blade. No other abilities. So you are SOL for Hidden Blades.
From the Combat Mechanics guide (http://forum.bioware...mbat-mechanics/):
Runes
- Rune damage is applied only on autoattacks and Spirit Blade attacks.
- Rune damage is applied separately instead of being added to the damage of attacks on which it procs.
- Elemental runes apply damage that is typed according to the element of the rune.
- Racial runes (runes that apply damage vs. certain creature types) apply physical damage that ignores armor.
- Rune damage has a base_damage value equal to the stated damage value of the rune (in other words, a rune that grants +10 spirit damage will have a base_damage value of 10).
- Rune damage has an ability_multiplier value of 100%, except when triggered by Spirit Blade, in which case the value is 300%.
- Rune damage can critically hit, and does benefit from critical_damage_bonus and flanking_bonus.
- Rune damage does not trigger effects that proc on hit or effects that proc on critical hits.
- One exception is that rune damage will trigger the extra damage from Lightning Cage.