"The wise in heart are called discerning, and gracious words promote instruction" (Proverbs 16:21).
James really nails this Old Testament proverb in the New Testament with the truth to be slow to speak, quick to listen, and slow to become angry. This proverb says that those who have true intelligence are subtle; they are discerning.
"Discernment" is a great spiritual word that means to separate, to determine. In other words, and in this context, it means that the wise are subtle and lump everything together, not jumping to conclusions. BUT, allowing our words to be full of grace and pleasurable sweetness. THIS will promote and increase instruction. We're much more persuasive when our words aren't forceful.
I have learned, and am still very much learning this truth in the different roles of my life, and by great trial and error. When I served in the US Army, it didn't matter how instruction was given, just that it had to be obeyed. But, with that, came great, underlying bitterness, resentment, and a lack of respect.
It's true for most people, we are much better leaders and motivators when we take the time to listen without interrupting and without jumping to conclusions. We lead the best when we choose to build up rather than destroy.