Spirit related items:
Eileen's Doll//
This isn't needed to progress in the game. If you take it and put it in Henry's item box it will cause an extra haunting to appear over the box once Henry's apartment becomes possessed.
Holy Candle//
Used to get rid of spirits in Henry's apartment when it becomes possessed. Place the candle on the floor next to the spirit (where the screen is flashing red) and watch for the candle to burn out completely. The spirit may come back if you don't watch the candle burn out completely.
Sword of Obedience//
After knocking one of the victim enemies down, place this sword in them and they will stay down until you take the sword out again.
Silver Bullet//
Use this in Richard's revolver. It will take a victim enemie down in one shot. You will still have to use the Sword of Obedience on the victim to keep them down, though.
Ammo:
Pistol Bullets// Used in the pistol. I do know that the amount of bullets varies with what difficulty you are playing on. On easy you get 12, right now I'm unsure of the other difficulties.
Revolver Bullets// Used in Richard's revolver. I do know that the amount of bullets varies with what difficulty you are playing on. On easy you get 6, right now I'm unsure of the other difficulties.
Health:
Nutrition Drink// This recovers about a quarter of Henry's health. This is the same as the health drinks from the previous Silent Hill games.
Portable Medical Kit// This recovers about half of Henry's health. This is the same as the first aid kit from the previous Silent Hill games.
Ampoule// This recovers all of Henry's health.