Kucereus:
This is a letter of introduction which explains that you're allowed to engage into action in the Seed of Immortality area. The Seed of Immortality is a dangerous area though, but this letter says that an adventurer like you can be trusted.
If you can deliver this letter to Officer Tepios who's inside of the Seed of Immortality, he will also realize why I recommended you as a skillful adventurer.
Be advised that first you have to be teleported inside of the Seed of Immortality through a person called Jaedin who's at the Seed of Immortality Dock.
In addition, you have to acquire a Flying Transformed Object in order to move through the skies of Gracia. You can get it if you complete a simple mission given by Engineer Lekon, a dwarf located at 6 o'clock direction from here. Or, you can purchase Transformation Scroll from Officer Tolonis who's right next to him. Okay, good luck.