Muti protects against "creatures like the tokoloshe", a union official told the Farlam commission in Rustenburg on Wednesday.
Ishmael Semenya, for the police, was questioning National Union of Mineworkers (NUM) member and Lonmin employee Saziso Gegeleza on his knowledge of the use of muti (herbal medicine) before fights.
"I don't have the experience," he said, and explained that the only muti he was aware of was used to attract women.
Post mortem examinations of the people killed at Marikana last year had revealed fresh incisions on their bodies, Semenya said, and he asked why these were made.
"Sometimes, to protect people against creatures like the tokoloshe [an evil spirit]," Gegeleza said.
Semenya put it to him that if this muti worked against the tokoloshe, it would work even better against humans.
"I'm not sure if that's the position. What I know is it does have an effect on the tokoloshe," Gegeleza said.
Semenya also asked him to explain why he thought a large police contingent at Marikana had not deterred striking workers.
"I was far away from Marikana at the time the police was there," Gegeleza said.
The commission is probing the deaths of 44 people at Lonmin's Marikana mine in August 2012.
On August 16, 34 striking mineworkers were shot dead and 78 were wounded when police opened fire while trying to disperse a group gathered on a hill near the mine.
In the preceding week, 10 people, including two police officers and two security guards, were hacked to death.