Some topics are too touchy to talk about, though you might not know that at the time. You don’t know what’s happened to another person or how they will react to your opinions, so you can’t beat yourself up for saying something they react adversely to. However, if you know someone is sensitive to a topic, it’s your responsibility to remember that and be courteous.
The man with a sword carries it because of the power it has over others. He would be foolish to act as if his blade had no strength and could deal no damage. Remember the power your words have, and deliver them with care.