You'll find this in the second section of Iron Keep (with the walkways and greatbow-wielders). Climb the ladder in the back of the room to find a chest, but don't open it--it's a Mimic! Kill the creature, and it will drop this.
Climb Earthen Peak until you reach the poison pool before the fog gate. To the right of the gate is a lit passage; follow it, then make another right. In here are several poisonous enemies and pots, plus a chest. Well, the "chest" is actually a Mimic. Kill it, and it will drop these.
you first enter Doors of Pharros, look in the corner of the watery
chamber for a chest. Well, it looks like a chest, but it's a Mimic. Kill
it to have it drop this piece of armour.
When you first enter Aldia's Keep, look in the back left corner for an iron chest. Don't open it yet - it's actually a Mimic. Kill it, and it will drop this.
Dropped by Titchy Gren at the Undead Purgatory bonfire (you must kill him).
Can be purchased from the old merchant at the Cardinal Tower bonfire in Forest of Fallen Giants (must have killed Titchy Gren).
Dragon Acolyte Mask
There's a petrified cyclops on the third floor inside Aldia's Keep. Restore him with a Fragrant Branch of Yore, then defeat him to have him drop this.
Drangleic Armour (Full Set)
in Forest of the Fallen Giants. After defeating The Pursuer, move ahead
to these broken walkways. Look below for ruins you can safely drop to.
On the way down these debris shelves is a corpse holding the Drangleic
Mail, Leggings, and Gauntlets.