Ariela giving the meal toi Zael
This side quest can be started after Chapter 7.
To start you must follow the eastern side of the river to the east of the Central Plaza, where you'll find a child complaining about his hunger. Return to Ariela's Tavern and she'll give you one of her meals. Return to the child and he'll give you a towel.
Take the towel to a sweaty guy on the Artisan's Way and he'll give you a book called The Art of Magic. Take the book to the Lazulis Castle (after Chapter 8.) In the library a child named Uril will change the book with another called Rules of Nobility. In the Castle Gate Plaza you'll find a women on some tables to the northwest that will swap the book for Precious Jewel.
Return to the Castle. On the second floor's hall will be a lady that will trade Zoran's Voyage Log for it. During Chapter 19, after being named a knight, go to the Dungeon. You'll find Zoran in a cell, and he'll give you his sword in exchange for the log.