Assassin
Assassinate: Kills the enemies generals (making fight easier)
Poison master: -5% strength of enemies.

Barbarian:
Gladiator: Gives a loot crate on winning a Olympic game.
Stone arm: +15% to stone production.

Chanter:
Mirth: Happiness decreases slower.
Raise morale: Enthusiasm is generated faster.

Cleric:
Communion: -5% charge time of divine abilities
Preacher: -5% to crusades or conversions cost

Druid:
Lifewarden: +1 birthrate (X times covinari's owned)
Woodspeaker: +15% wood production.

Knight:
Blacksmith: +15% metal income
Vanguard: +2% health and attack to armies (X times covinari's owned)

Paladin:
Crusader: 100% increase to the effectiveness of crusades.
Piety : 15% faith income

Ranger:
Eagle eye: Chance for finding enchanted fragments when raiding ruins*
Master hunter: +15% food production.

Rouge:
Looter: +25% from raids
Thief: +15% coin production.

Wizzard:
Convention of elements: +5% to all resources income.
Divination: Give access to special events.

(*eagle eye did not do enything for me, but might be due to low glorie)