For Zhaitan and Mordremoth you answer your own questions (except for Zhaitan it had more to do with the particular type of cannon than having airships, which in turn had to do with the orb at fort trinity if memory serves, its been too long). As for why the commander was able to kill Balthazar, we are mindmelded with a dragon pup that is supposed to replace an elder dragon some day and wielding a relic of Orr (Rytlocks sword is plenty special), what is one god stripped of his power against that. Note that unlike when we had our chat with Kormir, standing in front of Balthazar did never blind us, ergo he never was a god at the point when we met him. Regarding Kralkatorriks involvement, he had just been given a spanking by Balthazar using Aurene (the story clearly establishes that Kralkatorrik is his own biggest weakness, and Aurene being Glints off-spring makes that true when it comes to Aurene, which is why Balthazar chose to use Aurene to begin with). Of course after Balthazar dies, Kralkatorrik gets charged right back up again, but during the fight he is pretty weakened.