Detect Secret Doors

Herve locates all secret doors within 10 feet of it as if it possessed a passive Perception score of 20.  Secret doors, for the purpose of this property, include any intentionally concealed doorway, hatch, entrance, or other portal designed to be unrecognizable from the surrounding environment by its creator.  Thus, the sword would locate a shifting bookcase that conceals a passageway, a portion of stone wall that pivots, or a trapdoor hidden underneath a carpet, but not a doorway concealed by a cave-in or a trapdoor located underneath a collapsed ruin.  You know the exact location of the door, but not always the means to open it.  This property can be used up to three times each day, resetting at dawn each day.