From the Manual of the game:
Hakim's powers of persuasion are so strong that he can win over even the most stubborn opponent. Hakim always weighs up all the options in a calm and collected way and strives to reach an amicable solution.
Passive skill: Thanks to Hakim's knowledge, upgrading buildings costs less resources.
Active skill: Hakim can persuade a hostile battalion near him to fight on his side.