The only reference I can find to Spear Slaves has to do with pieces on the Kaissa board. Here are the two instances I found.
A brief exchange followed, like a chain reaction, neither man considering his moves for a moment, First Tarnsman took First Tarnsman, Second Spearman responded by neutralizing First Tarnsman, City neutralized Spearman, Assassin took City, Assassin fell to Second Tarnsman, Tarnsman to Spear Slave, Spear Slave to Spear Slave.
Mintar relaxed on the cushions. "You have taken the City," he said, "but not the Home Stone." His eyes gleamed with pleasure. "I permitted that, in order that I might capture the Spear Slave. Let us now adjudicate the game. The Spear Slave gives me the point I need, a small point but decisive."
Marlenus smiled, rather grimly. "But position must figure in any adjudication," he said. Then, with an imperious gesture, Marlenus swept his Ubar into the file opened by the movement of Mintar's capturing Spear Slave. It covered the Home Stone.
Mintar bowed his head in mock ceremony, a wry smile on his fat face, and with one short finger delicately tipped his own Ubar, causing it to fall.
"It is a weakness in my game," lamented Mintar. "I am ever too greedy for a profit, however small."
Marlenus looked at Kazrak and myself. "Mintar," he said, "teaches me patience. He is normally a master of defense."
Mintar smiled, "And Marlenus invariably of the attack."
"An absorbing game," said Marlenus, almost absent-mindedly. "To some men this game is music and women. It can give them pleasure. It can help them forget. It is Ka-la-na wine, and the night on which such wine is drunk."
Neither Kazrak nor myself spoke.
"Look here," said Marlenus, reconstructing the board. "I have used the Assassin to take the City. Then, the Assassin is felled by a Tarnsman - an unorthodox, - but interesting variation."
"And the Tarnsman is felled by a Spear Slave," I observed.
"True," said Marlenus, shaking his head, "but thusly did I win."
"And Pa-Kur," I said, "is the Assassin."
"Yes," agreed Marlenus, "and Ar is the City."
"And I am the Tarnsman?" I asked.
"Yes," said Marlenus.
"And who," I asked, "is the Spear Slave?"
"Does it matter?" asked Marlenus, sifting several of the Spear Slaves through his fingers, letting them drop, one by one, to the board. "Any of them will do."
Tarnsman of Gor    Book 1    Pages 169 - 170
Most Gorean cities now, at least in the south, had accepted a standard tournament Kaissa, agreed upon by the high council of the caste of players. Sometimes the changes were little more than semantic. For example, a piece which once in Ar had been called the "City" was now identified officially as the "Home Stone" even in Ar. Indeed, some players in Ar had always called it the Home Stone. More seriously there were now no "Spear Slaves" in common Kaissa, as there once had been, though there were distinctions among "Spearmen." It had been argued that slaves had no right upon the Kaissa board.
Beasts of Gor    Book 12    Pages 43 - 44
