An enchanted spear owned by the god Lug in Irish mythology.
In battle, the weapon tore through the enemy ranks like lightning. After battle, it had to be quenched in a cauldron full of blood to render it safe to handle. When the hero Celtchar hefted it, blood dripped from its tip, landed on his body, and killed him.
Proponents of a Celtic origin for the Grail legend have identified the Luin of Celtchar with the Bleeding Lance, which also bled from its tip. In addition, the Luin is associated with a cauldron, which some advocates see as the origin of the Grail.