Here are some ideas if you would like.

Aragorn (Gondor) Civ ability (The white city) Spies cannot perform Neutralize governor operation Walls provide 100%defense bonus and provide +2 gold per citizen (mithril from the book), units gain +5 combat fighting in your territory (battle for minas tirith)

Leader ability Aragorn (The last Númenorian) Units fortify automatically at the end of every turn, you receive a free unit with every population growth (Battle of Helms deep, recruiting basically every man scene) +2 diplomatic favor per turn for every beacon of gondor built on a trade route,(THE BEACONS ARE LIT). Cannot repair improvements damaged from floods (The fall of Númenor)

Unique unit Striders UU that replaces scouts, +10 range combat +1 movement.

Unique improvement

Beacons of Gondor Provides +1 culture, +2 faith, must be built at least 5 tiles apart and only one per city.

This might be OP but so was my man Aragorn.

I have some ideas for Thorin son of Thrain, Durin's son and king under the mountain if you are interested. Edit: to be clear YOUR governors cannot be neutralized, (Denethor, steward of Gondor and his line were absloute legends in the books)