How Did Ultima Weapon Get The Sword?

[Alexander]

Or maybe Ultima Weapon from VIII went to VII and stole it from Cloud.

Actually, Aeris stole Cloud's sword. Then she flied to FFVIII and gave it to Ultima Weapon. From there she flied to FFIX to say "I am your father" to Dagger in the Meltigemini fight. XDDDDDD