Divine Avenger should do more damage, due to it be split normal and elemental damage. A burning Oiler would reduce the elemental damage from Divine Avenger, but not the normal damage, in contrast to reducing Warmaster Rocket Hammer's pure elemental damage.
Also, just tested with my Level 6 Divine Avenger vs my Level 10 Warmaster Rocket Hammer. Against a burning Oiler at Depth 24 with no damage bonuses, my Level 6 Divine Avenger did 144 damage on the first swipe to the Oiler, and my Level 10 Warmaster Rocket Hammer did 98 damage on the first swipe to the Oiler.
Divine Avenger should do more damage, due to it be split normal and elemental damage. A burning Oiler would reduce the elemental damage from Divine Avenger, but not the normal damage, in contrast to reducing Warmaster Rocket Hammer's pure elemental damage.
Also, just tested with my Level 6 Divine Avenger vs my Level 10 Warmaster Rocket Hammer. Against a burning Oiler at Depth 24 with no damage bonuses, my Level 6 Divine Avenger did 144 damage on the first swipe to the Oiler, and my Level 10 Warmaster Rocket Hammer did 98 damage on the first swipe to the Oiler.