This breastplate has been made by the best of the best dragon Borns . Where to find: to the right. Corner of the cave. You will see a human sized compartment  if you go inside it will lead you to a room inside a chest is a breastplate. Oh yeah the room is 20 ft wide and 30 ft tall. Later when you come back there will be dragon borns you can convince them to let you have or you will be held hostage 

This armor consists of a fitted metal chest piece worn with supple leather. Although it leaves the legs and arms relatively unprotected, this armor provides good protection for the wearer's vital organs while leaving the wearer relatively unencumbered.