Armor (plate), legendary (requires attunement)
While you're wearing this armor, you can speak its command word as an action to gain the effect of the etherealness spell, which last for 10 minutes or until you remove the armor or use an action to speak the command word again. This property of the armor can't be used again until the next dawn.
Plate consists of shaped, interlocking metal plates to cover the entire body. A suit of plate includes gauntlets, heavy leather boots, a visored helmet, and thick layers of padding underneath the armor. Buckles and straps distribute the weight over the body.
Notes: Utility, Combat, Warding, Str. 15 Required, Stealth Disadvantage
AC?
It does say "Armor (plate)", so it's plate and as such the AC should be 18
I like giving random descriptions on how items or creatures can fit into the Eberron setting. Here's a one of those.
Wide magic dictates that legendary items can't be manufactured in the Five Nations or even Aerenal at present. The planes, however, have no such restriction.
"This husksteel set of plate armor was forged by the Smith of Souls from the memories of spies and secret-keepers; so long as your presence is undetected and your knowledge vast, you are a viable candidate to have your memories tempered to form one of these suits."
For a legendary, this is pretty crappy. Not even a bonus to AC (ex. Efreeti Chain)