And I even have a Bahamut's Sword there. Maybe it’s not quite right, but replacing it with a fully upgraded Aesculus doesn't really boost damage that much, even considering critical hits (without crits, it noticeably reduces damage), and health actually decreases.
I only need Ixaba for future plans; maybe I'll use it when creating Agni (but it's not a priority; I'm more likely to focus on crafting Zephyrus in the air right now).