I couldn't finish 'em. Looks like this's gonna get complicated.
Velis is a boss in Final Fantasy XII: Revenant Wings. He is fought in Mission 5-4: The Dance along with the Judge of Wings. He is later fought in Mission 7-3: Where the Heart Lies. His attack pattern and appearance are exactly the same as Odin. Odin is unlocked on the Ring of Pacts after Velis is defeated, suggesting that the two are connected, or are the same being.