Eugen Petersen quoting in The Rotting Goddess describes two types of Hekate representations, one with libation bowls and long torches, and the other with short torches, whips, serpents and keys. Roman era figures show the whip or scourge, a knife and small torches. It has also been interpreted as a rope symbolising the umbilical cord and her role as midwife, perhaps also of psychopomp 77.
(From the Hekate ritual at PantheaCon 2013) “The knife for making sure the road is open, and the scourge for making sure of the going!”
77 Rabinowitz, J. 1998. The Rotting Goddess: The Origin of the Witch in Classical Antiquity,
The Symbols of the Goddess Hekate