Lancelot's advantages are: decades of rigorous training and drilling; actual battle experience (in which dying is definitely to be avoided); and a not-insignificant amount of natural aptitude and endurance. Of these, two give him an edge over Magnus and his einherjar enhancements. But now that Magnus has been training with him for a while, and taking things seriously to boot, Lancelot is finding that it's rather difficult to keep up with him. He finds that he has, of late, been tempted now and then to pull the sorts of stunts he would in a real melee tourney back at court. To take what might feel to Magnus like a cheap shot, or to disarm him; to go hard enough to push Magnus back and eventually put him on the ground. He doesn't ever do this, though.

Magnus still has things to learn, refinements to make -- everyone does. But he is terribly fast, and Lancelot has to put in real work to deflect or block his whirlwind of strikes. He manages to do this, though it's a near thing, and then he shifts enough to twist and snake around to hit Magnus' thigh with the flat of his blade.