Easy "Two-Faced" Trophy
Enter the Stonecutter's Court then find the Jeweler's Shop to the left of the guards that are talking to each other, standing in the light. Enter the shop, knock out the guard to the left of the entrance, then turn to the right. Find the three cabinets below the red drapes. Use a lockpick on the center cabinet to get the first mask. Then, turn around and sneak into the cellar. Avoid the person working at the desk while moving to the rear left corner of the workshop. Interact with the painting and use the secret switch to unlatch it to find a wall safe. Enter the combination "739" to open the safe and collect the other item.
Safe combinations
Use the following combinations to open the corresponding safe.
Chapter 1: Lockdown - Serendi Jeweler's Cellar: 739
The City Part I - Miss Scarlett's Town House: 824.
Chapter 2: Dust to Dust - Workshop: 314
The City Part II - Baron's Way South (South Quarter): 842
Chapter 3: Dirty Secrets - Upper Level: 573
Chapter 4: A Friend in Need - Safe Chamber: 319
Chapter 4: A Friend in Need - Safe Housing: 018
Client Job 4: The Carnal Connoisseur - Wine Cellar: 812
Chapter 5: The Forsaken - Treatment Center (Third Floor): 731
The City Part V - Archie Maxwell's House: 776
Chapter 6: A Man Apart - First Floor: 889
Chapter 6: A Man Apart - Waiting Hall: 017
Chapter 7: The Hidden City - Loading Docks Interior: 673
DLC: Client Job: The Bank Heist - Outer Vault: 632