God has given us many tools and also wants to produce the fruit of The Spirit in and through us. Sometimes people forget that things like harshness, anger, etc are not part of the fruit of The Spirit.
Furthermore, the scripture reminds us that Love is patient, love is kind...(See 1 Corinthians 13) but sometimes others in our lives or even ourselves lack these very things in relation to others. I'm also reminded of Proverbs 16:24 "Gracious words are like a honeycomb, sweetness to the soul and health to the body."
As always, our words can bring life or death to the hearer. Our words are more powerful than we realize because those words whether good or bad, stay with the hearer and sometimes much longer than they should when we speak unkind words. This is why I've shared in the past that the old saying, "Sticks and stones may break my bones but words may never hurt me," while a nice sentiment, it's not really true because words do hurt and it takes more time mentally and emotionally to heal from words spoken to us.
While there are times where we need to be more firm in our communication, we need to remember that even in being firm with others who have wronged us, or who need correction, or that we disagree with, we need to season that with grace so we can represent The Lord more effectively.