When Catherine throws her last knives, you can see that one of them was very close and that all Trowa does is break a sweat. If Catherine was right and Trowa was ready to die, then why would he sweat? And besides, we learn soon after that he would never do so. Additionally, Catherine and Trowa soon confirm that she did hit him. So we can assume that the knife must have skinned Trowa and that the drop of sweat was actually blood that was edited for the American version, thus spoiling the surrealism of the series' main characters.