After you finish first part of "The Vision" in Dumnonia travel to the north from West Mersia to the settlement Eaglades in the Bedegrainу forest. There you will find second part of this quest. First of all you will need to choose how to get to the tower. It does not matter which of three options you will choose. When you be inside there is Pendant of Llefelys (+4 loyalty to the hero) in Alcoves and The Thrusful Sword (+3 level to Famous Leader Skill) (or some other weapon) in the unseelie room.
Hero lvl 13 is enough to accomplish this task with only 1 fight skill.
After that you will see third part of the quest - The Dragon's Heart.