Given scene/plot descriptions from movies or TV shows, and given a specific question about the scene, summarize the question into a title

Let me give you an example: At the beginning of the movie Gangs of New York, Priest Vallon tells his son not to wipe the blood of the blade after he's cut himself shaving, saying "The blood stays on the blade". I've watched the movie multiple times, but can never find what the meaning behind that phrase is. Anyone able to shed some light on this?
The answer to this example can be: What's the meaning behind the phrase "The blood stays on the blade"?
Here is why: A person gives a detailed description about a scene from the movie Gangs of New York and asks the meaning of a said phase in the scene. The question is summarized as What's the meaning behind the phrase "The blood stays on the blade"? for easy indexing the next time someone searches for a similar phrase

OK. solve this:
In the episode The Raiders Minimization of The Big Bang Theory Amy ruins Raiders of the Lost Ark for Sheldon by making the following claim: Indiana Jones plays no role in the outcome of the story. If he weren't in the film it would turn out exactly the same. [...] If he weren't in the movie the Nazis would have still found the Ark, taken it to the island, opened it up and all died... just like they did. Well, the Ark ending up in the warehouse (probably) wouldn't have happened without Indy, but aside from that, would Belloq and the Nazis have met the same fate even without Indy's meddling? My question: Is Amy's assertion correct, did Indiana Jones play no role in the outcome of the story?
Answer:
Is Amy right about Indiana Jones being irrelevant to the outcome?