Training salt was originally developed by the harsh Sarpathians for their final training session before a young man was granted the title of warrior. Its use spread to other militant societies and groups as ways to prove their toughness and bravery in the face of danger, pain and the threat of death.photo © 2004 Dawn Endico | more info (via: Wylio)
From these almost admirable uses, its use has further spread to slavers and to torturers.
Training Salt
This alchemically treated salt is finely ground and clings to any metal it is applied to giving it a crystalline sheen. It must be stored in watertight containers, usually made of ceramic. A standard container of training salt has enough to coat one two-handed sword or two one-handed swords or six daggers or eight spear heads or a dozen arrows.