Ruling Malebazus is one thing, but Aroesus had control over the imprisonment of deities on Lake Sharzunates. So in a sense, her authority would be under that of Aroesus who would keep her as a warden over mortal souls. When Aroesus dies, Malebazus becomes way more chaotic as a result.

As to killing deities, it's generally more difficult to kill the Dream goddess within the dream or the Sea deities in the ocean and so forth. We'll have to fine tune that for some concepts, but I think it could hold. For example, a deity of violence might be undone by subterfuge.