Spear vs. Sorcerer, spear wins

At the last moment, he reached out and snatched the Spear from the air, catching it just behind the head. He felt its momentum and its mass, far greater than anything he could have expected. He let the weight of it turn him around in a half circle, bringing him to face the heretic once more and with a snap of his arm he set it onwards to bury itself in the Chaos worshipper's chest. Even Sergius's vast, sorcery riddled body could not withstand the weapon that had wounded Magnus himself. It passed right through him and almost out of the other side.

Space Wolf Omnibus pg. 758