So i'm making a list of the traits you receive when defeating the Legendary Lords contained in this mod:

What I've got so far:

Defeated Helmut Feuerbach (Talabecland) : The Gift of Gab
"If you don't hate me yet, don't worry... Your time will come."
Income from raiding: +20% (Lord's Army)

Defeated Aldebrand Ludenhof (Hochland): Predator of Drakwald
"We hunt them to keep their numbers down. It's good for the environment."
Leadership: +4 during forest battles
Ward save: 10% during forest battles

Defeated Elspeth von Draken (Wissenland): The Graveyard Rose
"Her Death Magic, Magicc talismans, and mystical artefacts have counted for naught in the face of superior arms."
Research rate: +10% (factionwide)
Spell resistance: 10%

Defeated Valmir von Raukov (Ostland) Shadow Forester
"And as we lay here prostrate, Nordland and Talabecland plot to land the final blow..."
Weapon strength: +15% when defending
Leadership: +5 when defending

Don't hesitate to complete this list in the comments :)