I kinda figured since we got Ultima so early, we'd allude to Omega Weapon at some point. I'm actually wondering if Omega will survive his Raid and fuse with the remains of the Ultima Weapon or something to make XIV's version of Omega Weapon, even if the two are usually unrelated.

Or maybe it's tied to that thing that destroyed the Isle of Val (I think?) back in ARR with a power similar to the Ultima spell that was never really followed up on?