You can forge and alter gear at the blacksmith. After completing the first main mission, you will unlock the world map and can talk to the blacksmith between missions. To forge an item and get the "Latest Masterpiece" trophy, go to "Blacksmith" - "Forge". You get crafting materials by disassembling gear in your inventory. This can also be done at the blacksmith. Some materials are mission rewards. To refashion an item and get the "Refashion" trophy, go to "Blacksmith" - "Refashion". You can give gear in your inventory the appearance of other gear that you have previously found. You can even give light armor the look of heavy armor without changing any stats or equip weight.