Whistle of Pacifying the Dead

This whistle is a wooden flute with six round holes. It was found in the possession of Plamenka, polevik matriarch, as she slumbered in Crows' Meadow Warren. After Chonkorchuk divined enchantment magic emanating from the whistle, it was taken and studied by Raskel, who discovered its function. Through an inspired guess, he asked Plamen to sing a lullaby from his childhood that Plamenka would sing to him, and then reproduced the song in the room where most of the skeleton guardians were kept. Playing it caused them to cease all activity for 1 hour.
It is not clear whether the whistle is keyed to the particular skeletons in the Warren, or whether it can be used on other Walking Dead. If the latter is the case, it is not yet clear whether the whistle will have such a powerful effect on them, and whether any effect requires specific keying. It is also not clear whether the whistle is a charged item or not.
The whistle remains in Raskel's possession.