The play ends with Eddie being stabbed with his own knife and dying. On top of that, Marco twists Eddie's arm around weirdly, such that its Eddie's own hand that drives the blade home. Does this happening have a larger symbolic meaning? Outlook is good. Let us analyze.
Well, we know that all the problems come from Eddie's refusal to let Catherine go. Also, Eddie is the one that betrays his community. And, of course, it's Eddie that brings the knife into the duel in the first place. It would seem, like most tragic heroes, Eddie is the cause of his own destruction. The fact that he dies by his own knife seems to be a none-to-subtle symbol of his self-destructive path. We also talk about this in "What's Up with the Ending." Go forth and peruse.