Just to be clear, patch 2.x in RoS current state of the game - black weapons are no longer bugged wherein various items adding percentage of X elemental dmg no longer applies to black weapons, right?
Or perhaps legacy items will still work that way. I notice that items now are listed like "Lightning skills do +20% more damage", as opposed to "20% more lightning damage". Maybe that's how they "fixed" it?
And for that matter if that is the case, then if you have a wizard or monk lightning build and gear.. something like your Thundergod's Vigor proccing will not have it's damage increased by "lightning skils do +20% more damage", right? Same for the fulminator, and so forth?
Annnnd... if you have a weapon that does X amount of holy, lightning, fire, whatever... then all those items that add "lightning skills do +20% more damage" won't make any difference to the dmg type of your weapon, but only to the skills you're using?
I don't know the answer to your first questions, but testing has shown that Thundergod's Vigor's proc IS increased by +% lightning skill damage. I've seen reports that Odyn Son does as well, but also seen it said that it doesn't. On the other hand, Thunderfury's proc does NOT scale for sure, neither does Fulminator, so the reality is... some things scale and some things don't. For whatever reason, there's inconsistency and Blizzard has been silent about why that is, so far. Need moar testing.
As for a weapon that simply has +fire damage as its extra damage roll (as opposed to +black damage), no, +% elemental skill bonuses do not scale that at all. The only thing that has any effect on a weapon's bonus damage affix is the Crusader Holy Cause passive, which boosts the damage of a weapon with a Holy damage affix by 10%.
Or perhaps legacy items will still work that way. I notice that items now are listed like "Lightning skills do +20% more damage", as opposed to "20% more lightning damage". Maybe that's how they "fixed" it?
And for that matter if that is the case, then if you have a wizard or monk lightning build and gear.. something like your Thundergod's Vigor proccing will not have it's damage increased by "lightning skils do +20% more damage", right? Same for the fulminator, and so forth?
Annnnd... if you have a weapon that does X amount of holy, lightning, fire, whatever... then all those items that add "lightning skills do +20% more damage" won't make any difference to the dmg type of your weapon, but only to the skills you're using?
As for a weapon that simply has +fire damage as its extra damage roll (as opposed to +black damage), no, +% elemental skill bonuses do not scale that at all. The only thing that has any effect on a weapon's bonus damage affix is the Crusader Holy Cause passive, which boosts the damage of a weapon with a Holy damage affix by 10%.