https://www.bg-wiki.com/ffxi/BGWiki:Ultimate_Weapon_Augments
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After you obtain a Key Item from any zone, or turn in 10,000 job points for any category, you must now ask Oboro about each weapon type you are able to upgrade.
Quote:
He will then take the Key Item Mask of Light from you, tell you that you may now upgrade that category of weapons, and then return said mask to you.
Did you do these two steps?