Obtained from the Dominion Sergeant in Abyssea-Altepa for 2500 Dominion Notes. Out of all the augmented weapons you can purchase with Dominion Notes, these sell the highest to NPC alongside with the Great Katana Yukitsuga from Abyssea-Grauberg. These both sell at 7,152 each with max fame.
This is no longer 1000 Dom notes, its 2500 now SE updated it but if you want a decent weapon quickly this is for you because who knows whats in store at Lv.99