"It's a death mask without a mouth."
— Item examination.
It is one of the four Death Masks needed to release the coffin inside the underground crypt. The mask is to be placed on the statue with the "A stone statue with a hole where the mouth should be." localization upon examine.
The "Mask without a mouth" can be retrieved from the Spencer Mansion's Portrait room after completing a puzzle involving stained-glass windows. It will be in an outside section next to the gate leading to the cemetery behind the hall.