We all know AoC has already 20 years, and some of the civs are in need of updates to be a little more acurate or to keep up with decades of META evolution.
BRITONS
Xbows replaced for longbows, gets billmen as the new UU
CELTS
Gallowglass as their new UU, a slower version of Woads but with 1/2 armor and a little more expensive
SARRACENS
New mameluke, for the most part it will change the unit from a fantasy scimitar thrower to a CA. Same anti cav role but with bonus armor against mounted archers attacks (similar to shotels vs cavs)
MONGOLS
New “Scourge” UT to replace Nomads, cavalry units do bonus dmg against vills, TCs and houses
HUNS
Atheism UT also improves the resistance to monks… reduce monks conversion chance per second from 25% to 15%
TURKS
Gets Genitours
TEUTONS
New unit from barracks “Landsknechts”, a fast unit that can fight with swords (to get more base dmg and bonus vs eagles and buildings) or switch to pikes (for a bonus vs cavs), but will recieve all the bonuses against the spear armor