Dalinar giving up his Shardblade to save Sadeas' bridgemen. It may have saved Kaladin's faith in humanity in general and the lighteyes in particular.
Dalinar: How much is a man's life worth?
Kaladin: The slave traders say about two emerald broams.
Dalinar: And you?
Kaladin: A man's life is priceless.
Dalinar: Coincidentally, that is the exact value of a Shardblade. So today, you and your men sacrificed to buy me twenty-six hundred priceless lives. And all I had to repay you with was a single priceless sword. I call that a bargain.