Fire Poker

Crypt Storeroom (Orphanage B2): south-east corner. Go behind the altar in the Underground Chapel (secret door), throw the wall switch, pull out a bottom-shelf coffin, climb over the top of the barred door and drop onto the mattress. Unlock the gate from inside.

Hook the ladder on the west side of the Underground Chapel, behind the secret door, and climb to the ARK Storage Closet: you escape The Children, who don't follow.

With Chloe it is not a weapon: it is a key item.