Related
Found In
Deist Cavern B2
The Pendant allows you to speak to Wyverns. It is found on the corpse of a dragoon in the Deist Cavern.
A pendant worn by the girl who pilots the MagiTek armor
Found In
Narshe Town
The Pendant is in your inventory from the start of the game, though it doesn't actually do anything. It is mentioned in the plot several times, however.