This is a bit of an easter egg hidden within (FF15) Final Fantasy XV, as Nyx Ulric isn’t actually a character that appears within the game.
Instead Nyx Ulric is the character that appears during the Final Fantasy XV movie, Final Fantasy XV: Kingsglaive. He is also now available in the mobile / Android game Final Fantasy Brave Exvius too.
Thus having his weapons of choice, the Kukris Daggers is quite the Easter egg and they are not too bad a weapon neither.
However, in order to get them and be able to use them you will have to do quite a bit of work and effort, you will also need to be quite far into the story too.. (End-game area)
Step 1) Return or be in Insomnia which is the very last area in the game
Step 2) Fight Ifrit
Step 3) Board the Elevator to spawn the Iron Giants
Step 4) Kill or ignore the Giants and exit back out of the gates and search for a ‘Psychomancer’
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