The seneschal struck Joseph of Arimathea in the thighs with a pagan sword, when Joseph wandered into a Saracen castle in the forest of Broceliande. Half of the sword broke off and remained in the wound. After he converted the castle and its lord, Matagran, he miraculously removed the broken piece of metal from his thighs, and proclaimed that the two halves would not be rejoined until the one handle it would come and achieve the Grail. The broken sword was held in great honor at Mategran’ts castle, at least for a while.
Malory omits this early history of the sword, but tells how Eliazar, Pellam’s son, brought it to Carbonek during the Grail Quest. Gawaine, Perceval, and Bors failed. Meanwhile, the piece which had been stuck in Joseph dripped blood constantly. Galahad found them and at the end of the Quest he soldered the broken pieces by simply setting them together with his hands. Galahad gave the sword to Bors.
Kissing the sword would keep whomever kissed it safe from being mortally wounded for the day.
Vulgate Estoire del Saint Graal | 1220-1235
Vulgate Queste del Saint Graal | 1215-1230
Le Morte Darthur | Sir Thomas Malory, 1469-1470