I am stuck! (Bug?)

After I crash the rocket to the meteor, I went to Cosmo Canyon, long story line bah bah bah.
Shouldnt i be able to fight Diamond Weapon?? The guide says I use highwind fly from cosmo to midger and I will fight diamond...

But I can see no weapon, no diamond, no ultimate, no underwater weapon... what the heck is going onnn LOL

And can anyone teach and explan clearly how can i get a golden chocobird?

try flying over the northern crater.

Gotta go to the Ancient city from Cosmo Canyon. Then find the Key of the Ancients underwater, and back to Ancient city.

I got it thanks guys.