I've noticed a few other INFJs with the following behavior...
To not say anything unless one really means it. A person with few words. One who understates. Word of honor. What is said is what one meant. One whose words are binding.
Starter questions (open to all types):
It's an archaic notion, word of honor.
Do you believe in or follow the principle of "word of honor"
If so, why is honor so important?
It seems like for people who believe in this, they often do not readily trust others. There is a tendency to question the intent behind other people's actions. Is that true or not in your case? Why?
If you do not, why? Is the notion out of date? Foolishness?
What do you think makes a person more (or less) likely to follow it?
Are there any particular types that seems to you to take that principle to heart?
And whatever else you can come up with related to this... open floor ^^