Gomchen of Lachen
Type of Spiritual Experience
The Dorje mentionned here is another term for the Vajra. The apron may have the same symbolic significance to that used in for example freemasonry, but here as I do not know I have not made the link
A description of the experience
With Mystics and Magicians in Tibet – Alexandra David-Neel
One evening, the gomchen of Lachen appeared with all the trappings of a magician: a five- sided crown, a rosary-necklace made of one hundred and eight round pieces, cut out of so many skulls, an apron of human bones bored and carved, and in his belt the ritualistic dagger (phurba).
Standing in the open, near a flaming fire, he drew magic signs in the air with his sceptre- dorje and stabbed the air as he recited incantations in a low voice.
I do not know which invisible demons he was fighting, but in the fantastic light of the leaping flames he certainly looked like a demon himself.