Its the sexy kind! Its a type of armor that was previously available for purchase on consoles. But its out of circulation now so either its a long long time player having it, or a graphical glitch.
It is a 75% gold, 50% souls, 0 % exp armor called Ebony Armor.
It is a visual glitch related to Deathknight Armor. In the beta, there was no Deathknight Armor; instead, Ebony overwrite it. They didn’t fully fix the visual for it.