Gods or Creed (Side Quest)
A side quest in the realm of Aten. Start it by searching among the cages in the Chambers of Reflection.
Free the old man, but don't pick him up right away. The commotion will have drawn attention from nearby guards, who you should dispatch while you're still free-handed.
You might take a moment to snipe any other hostiles in range, then return to the old man and carry him home.
His 'home' seems to be an underground temple. Set him down by the central altar as indicated.
Speak with him to get three new quests, The Hawk, The Cat, and The Ibis.
Each of these miniquests involves retrieving an idol from the marked spot on the map. When you have all three, you'll need to dispatch Akhenaten as part of the Heretic quest (if you have not already done so).
With all these things accomplished, return to the underground 'house,' and speak with Khui one last time to win the Amun's Might sword, and complete the mission.
Note that you can examine the figures afterward for little personal anecdotes from Bayek.