- Unobtainable via normal means.
According to the tales, it was created by a Rivaini seer who lived high on the cliffs overlooking the Amaranthine Ocean. The woman took inspiration from the harsh winds and stinging rain that buffeted the coastline, and fashioned a cuirass that was as beautiful and cruel as the storm. As a finishing touch, the seer plucked the howling wind right out of the sky, and bound it within the armor. It is said that the winds of the Amaranthine Ocean will always favor any who possesses the cuirass.This story may be true, or it may be a complete fabrication. However, one thing is certain—plenty of superstitious sailors have fought and died over this legendary object, risking everything to be able to bend the wind and the sea to their will.
—From Codex entry: Cuirass of the Winds
According to the official guide, this chestpiece is supposed to be looted/received from Castillon in Act 3 during the companion quest No Rest for the Wicked. However, as of patch 1.04, it doesn't drop.