Ballista

Skin becomes a matte bronze, eyes glow blue with no pupils. Player gains +1 AC, is vulnerable to lightning damage, gains Darkvision and has "Timeless Body" aging 1 year every 10 years. 

The "Bronze Carapace" gives the bearer the ability to link with and control an Ancient, arcane, artifact code named "Ballista." The "Ballista" is a shape shifting, semi-sentient, mechanical construct that acts as a familiar to the bearer of the "Bronze Carapace." When not deployed in it's Battle Form, Ballista can rest as an ornament on the player (e.g. tiara, choker, armband, bracelet, etc.) Or it can wander around freely, like a pet if you choose (give control to the DM or narrate yourself). Additionally, you can instruct verbally or telepathically to augment the Ballista's form to create a single, simple tool. Or reconfigure to serve utility functions  (i.e. tripod to hold a fist sized magnifying Chrystal, wrap around a hot tub cup and act as a handle, handcuff a captive, etc.)