"à part de lui pickpocketter son journal"
Il suffit de le lire dans son inventaire, pas besoin de prendre l'objet.
J'ai trouvé ça sur le wiki :
360 If the player enters Frostmere Crypt before obtaining the quest from Eisa, and then exits the dungeon, she will have disappeared. Therefore, the player is unable to start the quest.
Solution: proceed through the crypt and into the Frostmere Depths. When you get to the altar search Ra'jirr's corpse for the Pale Blade and place it upon the altar. If you pick it up again, the quest will begin. You can choose to kill the Pale Lady or simply place the sword on the altar again.