From Destinypedia, the Destiny wiki
Armor Ornaments are cosmetic shaders for Exotic armor. Introduced in the Rise of Iron expansion of Destiny, Armor Ornaments can be earned through completing 390 versions of raids on the weekly rotation, Trials of Osiris, and Iron Banner. Returning in Destiny 2, Armor Ornaments can be purchased through Eververse, earned from Iron Banner, or obtained by decrypting Bright Engrams.
Destiny Armor Ornaments
Destiny 2 Armor Ornaments