First thing first. Balthazar is not the god of war when we fought him -- he's just a powerful Fire Elementalist with a gigantic sword. According to Kormir, there is a new god of war. So without the power of the god of war, Balthazar is trying to regain these lost powers by absorbing the Elder Dragons. Second, Zhaitan is not a fighter, if he is, he's a very weak one. Zhaitan is nothing but a Zombie master, very weak and only powerful through the numbers of his minions. We didn't kill Mordremoth until we stabbed Trahearne with Caladbolg. Mordremoth was about to come back using Trahearne and only the power of Caladbolg can effectively kill Mordy. Then when it comes with Primordus, we were planning to use a machine that Balthazar stole. So yes, the commander is not an all-powerful being.