From the Abaddon's Gate mission dialogue:
Kormir: "No. Yes. Kormir. And much more."
Party leader: "Abaddon?"
Kormir: "No. His power. His knowledge. But not him. His will is broken. There is a new god of secrets. There is a new day."
So, we know that Kralkatorrik and Aurene both absorbed something from Balthazar. We also know that when Kormir absorbed something similar from Abaddon, she also obtained his knowledge. What if Kralkatorrik just absorbed Balthazar's 2000+ years of knowledge regarding the secrets of the gods, military strategy, the strengths and weaknesses of different weapons and the various tactics used when employing them? That would make Kralkatorrik much more than just a super powerful Elder Dragon; it would effectively make him the most brilliant military mind on the planet with power surpassing that of any god.
Either that or Aurene inherited some of that knowledge and is probably a better commander than we are now...
EDIT: Also, if Kralkatorrik does enter the Blood Legion homelands, perhaps we could expect an epic showdown between Kralkatorrik, the scion of Balthazar's military genius, and the three High Legions of the charr. Who will win?! Mortal Military Machine, or Immortal Military Genius? Dragonbowl 2019.