The Ancient Shadow Armor set consists of rare drops from all of the Eaters in the Corruption. Like all ancient armor sets, the full set looks a little different than normal Shadow Armor. The scale-mail offers 7 defense, and the Greaves and Helmet offer 6 defense each. The full set buffs the wearer with 15% more movement speed, giving it the exact same stats as the normal Shadow Armor set. Armor from this set can be combined with armor from the normal Shadow Armor set to get the set bonus, although the visual blur from wearing a full set does not occur when the sets are mixed.
As the name implies, it is the version of shadow armor before 1.0.3, similar to other ancient armor.