Besides Haki & regular DF skill, we should also consider the possibility that they fought with Awakening
. I saw one comment on fb I liked, which said that:
"The reason Oda didnt show anything of Aokiji vs. Akainu was because they fought with Awakened Logias, and at that point in time, we didn't even know what Awakening was. Oda didnt wanna spoil us with a too early introduction of the DF Awakening."
I find that quite a worthwhile thought.
Not just the Awakening, Oda might still have more new powers
up his sleeve, and since Aokiji and Akainu are both top tiers, they'd use those powers in battle, hence Oda cannot show it to us too soon, to not reveal the new powers we will see in OP's future.