Through years of misuse, makeshift repairs, scarcity of materials, and constant use, it is a rusty, highly stylized suit of power armor. The left arm of the suit was replaced with the sleeve and glove of the raider iconoclast armor, a brahmin skull substituted for the left pauldron, an icon of a skull strapped to the codpiece, and various bits and pieces of metal were used to patch holes in the structure of it.
This suit of armor is only worn by Ashur. He can be looted of it at the end of Free Labor, or by reverse-pickpocketing any well-repaired suit of power armor and taking it from him once he equips the new armor. It can also be taken without repercussions toward Pitt raiders by hacking the Mk V turret's control terminal, with 75 Science required.
Speaking to Midea or Wernher while wearing this prompts them to compliment on how good the Lone Wanderer's new "trophy" looks.
If the Lone Wanderer sides with Ashur during the final quest and lets Midea live and enters a conversation with her while wearing the power armor, regardless of how it was obtained, she will remark that the Wanderer has replaced Ashur completely, and [they] are just the same as "the old boss."
When worn, in the "EFF" section of the character's stats, the armor shows up as "Pitt power armor" rather than "Ashur's power armor."