To craft the armor, you will need, depending on what you want to craft, either the Ranger helmet, the Breastplate or the Greaves from each of the 4 Hardmode Armors as well as 50 Souls of Blight(20 for chestplate). For the Body and Leg Piece, you need additional 20 Souls of Sight for chestplate and 10 for the leggings to craft them. All pieces are crafted with the Mythril Anvil.
Ocram has a decent chance of dropping (11.11%) a piece of Titan Armor.
The blue color of the Titan Armor may come from Titan Glove item, even though these items have a focus of different bonus.