This quest clashes with A Shaman's Ransom. The Dragon Knight is forced to choose sides by either completing the quest for Svadilfari or Aurelius (by refusing this quest and slaying Svadilfari). If you aid the goblin leader, a fake, poisoned replica is given instead. Aurelius does not notice the swap and as soon as he lays his hands on it, dies from the noxious poison of the fake trophy.
When you return to cave, you find Svadilfari ungrateful and ready to cut down his benefactor as you are no longer needed. When his health gets low, Svadilfari will flee outside. Resume the fight with the renegade goblin leader in air.
The tactics do not differ from occasional winged bosses. The reward is an additional option.