The 2nd Floor

At the bottom of the stairs, give the suit of armor standing near the landing a wide berth — don't interact with it yet. Head into the small bedroom on the right, where a ghost sits undisturbed. Leave the ghost alone; there's no way to drive it off, only to avoid provoking it.

Collect the Gramophone, the Fireplace Poker, and the Matches on the mantle. Check the shelves by the door too — they hold Rifle Shells worth grabbing before you leave.

Cross to the other side of the landing and into a narrow hallway. The first door leads into a room with no light source of its own — light your now-full Oil Lamp before going in, then drop it just inside the doorway so both hands stay free to search while it keeps the room lit for a few minutes.

The Heavy Statuette is the one item worth prioritizing here; the shelves also hold Revolver Bullets for later. Pick the lamp back up and put it out with any other action once you're back in the lit hallway.

Head back to the landing and throw the Heavy Statuette at the suit of armor. It knocks the Knight's Sword loose without triggering a fight — a much better source of a reliable melee weapon than relying on the Old Cavalry Saber's limited durability.

The narrow hallway's only initially open door leads to the bathroom, home to a squat purple creature that can't be killed by anything in your inventory.

The flask inside the First Aid Box adds 20 health when drunk — since health has no visible cap, drink it immediately and drop the empty box and bottle to save space.

The room beside the bathroom holds more reading material, including Jeremy's Diary. Disturbing it triggers another rat-thing attack — optional, but a safe one to take if you'd rather not backtrack for the fight later.

With the sword, statuette room cleared, and diary in hand, head down the stairs to the 1st floor.