“Mechanically joined plates of an unknown metal, crafted with extraordinary perfection.”― In-game text
This is an Uncommon item, a rare drop or obtainable from faction specific merchants.
No known associated quests
This is the very best chest protection you can get as a warrior. If you have a Laminated Vest, you can start pruning your wardrobe. (Of course, you should probably keep your Ashen Chestplate around, since sometimes, you will find its stun resistance and the higher fire resistance to be useful.)