Tristan, who was always apprehensive and fearful of being caught unawares in some way, jumped to his feet, and as he did
so, the youth shot a poisoned arrow into his left arm, so close to the bone that he almost injured it. Feeling himself thus wounded, Tristan took hold of his sword and rushed at the youth who let fly another arrow, intending to shoot it right through his body; but he missed, for Tristan leapt sideways, and seized hold of the youth by the right arm—not wanting to strike him with his sword as he was not a knight—and flung him away from himself and hurtled him against a rock with such violence that he dashed the youth’s brains out, and instantly his soul parted from his body.

Prose Tristan