I have a Fire Aura Spellblade with Fulminate and Concentrated Current allocated in Surge. In my understanding, as Fire Aura doesn’t have its own skill tree, it should benefit from generic “more damage” modifiers allocated in the Surge tree when triggered by Surge.
According to my testing, this doesn’t seem to be the case. On the training dummy, a single stack of Fire Aura from Flame Walker deals 710 damage per tick. A single stack of Fire Aura from Surge also deals 710 damage per tick. Clearly no damage modifiers from the Surge tree are in effect.
As I had a +3 Jasper’s Searing Pride lying around, I went ahead and tested with Ride the Lightning allocated. That doesn’t affect Fire Aura damage either. Neither does Conduit with 100 Static Charges and Fire Aura converted to lightning.
Given that Ride the Lightning is supposed to affect even triggered Lightning Blasts, this definitely looks unintended.
Looks like Fire Aura doesn’t benefit from a triggering skill’s allocated tree at all. If this is intended, it should be clarified somewhere. Otherwise, it would seem like a bug.