This is about as obscure as the original, which seems to allude to some event not mentioned in the Saga.
The old belief was that by this means only could a ghost be laid.
Biorn is Icelandic for bear.
The stone of steel-god's bane in Thorstein; Bylest's kin is Hel, death. The leopard is Bessi Skald-Torfason; byrni's flame, his sword. Thoughts-burg, a warrior's head.