Because it bears similarity to the context of the last post, I'm just watching (now listening) to John Boorman's 1981 film Excalibur. I've felt compelled to write a post, having just passed this scene:
Now, let's put that in a D&D context. The player, possessing a +5 holy sword, which makes him king, from a position of certain success in the battle, instead hands the sword over to the enemy, then kneels in the water, with his hands below the surface. Name the RPG player willing to do this!
I think there will be many who will say, having seen the scene, not actually playing in a campaign with a +5 sword, "Sure, I'd do that." I doubt, however, that they would. It is almost impossible to imagine this, in any context . . . but take a moment as a DM and decide what you'd do faced with this.
Play the moment out as the movie does? Is that fair? Given that the player may have seen the movie, are we being counted upon to cave and recreate the scene? "Oh, he won't kill me ~ not after bravery like this!"
At the same time, what sort of moronic, jerk-ass, insufferable bastard of a DM would hack the player to death for daring to risk so much?
There is no right answer. We use dice for things like this ~ presuming that we can either make a reasonable decision as to what the odds should be or accept the die roll once it hits the table.
I think we have to admit that a moment like this, should it turn up in a campaign, tests the mettle of both the DM and the player. As well it should.
In any case, we come back around to the expectations of how both monsters and NPCs should react when faced with something unusual from a player.