"The Knight with the Two Swords" is an ingenious and complex development of the two closing motifs of the "Merlin." In the first place, "The Knight with the Two Swords" focuses on the ironic destinal forces which Merlin can only in part control. Trusting in God and in "adventure" — or Fortune — Balyn takes the sword that is rightfully his. He knows himself to be pure in heart — his winning of the sword proves it — and so he cannot believe he will kill the man he loves best. Neither can he believe, later, that he will strike the Dolorous Stroke. He does both. Moreover, every pure and good cause he undertakes results in catastrophe: in his self-defense against Launceor of Ireland he causes the death of the knight, and in his wish not to hurt the wrist of Launceor's lady, he allows her the chance to commit suicide. So it is with all he does. Even in striking the Dolorous Stroke he acts without guilt, unaware of the consequences. His limitation is simply that he is mortal — non-omniscient — and the limitation is underscored after every mistake either by the appearance of magic writing or by Merlin's prediction, through his greater foreknowledge, of what later catastrophes will come in these same places, perhaps as direct or indirect results of Balyn's actions.
The second motif developed from the end of the "Merlin" is that of vengeance. Every detail Malory has brought together from his widely scattered sources involves vengeance (usually as family revenge) or its ironic inversion, intentional or accidental betrayal by a member of the family or by a lover. In each case, the vengeance or betrayal of love is unpredictable for ordinary men. The damsel who carried her lover's sword to the Lady of Avilon could not know that, for mysterious reasons of her own, the witch would turn it into an instrument of monstrous harm. Arthur could not know, in sending Launceor after Balyn, that in acting on his own outrage (coupled with Launceor's jealousy) he would trigger far greater wrongs. Nor could Balyn know that in pursuing King Royns, he would rouse King Nero.
