That might be the case.
But compared to other types, INFJ's will be least cocky or
They seem to sensitive to others, and wouldnt say something harsh.
They do the things in peaceful approach.
Indeed they are effective, but they might do the things in peaceful ways, rather then other dangerous ways. So less likely to create fear in others, like the way ESTJ's or ENTJ's will do.
To explain the INFJ in battle... I need to tell you a story.
I used to play a war/economy based strategy game. Now I enjoyed peace... I enjoyed helping weak people... nurtering weaker nations under my protection... building a vibrant, peaceful empire.
When i was faced with threats... I used all my INFJ wiles. I would
-flatter them or disarm them with humor
-bribe them
-try to manipulate them into not attacking... or not being agressive.
But if they refused to stop. if they laughed in my face when I tried diplomacy... I would get to a certain point where I'd label this enemy as an "evil man"... an enemy of the peace.
And after assigning that definition to them... there were not many of my enemies that survived. I endevored to remove them from existance. It was almost like cleaning out the garbage...
-I would first manipulate all of my enemy's ally's into abandoning him, or at very least not coming to his aid.
-Then I would manipulate anyone else I could find into attacking them for various reasons. (I was quite good at this)
-Then I would verbally harass the person until I got them into a rage, making him lose sight of reason
-Then I would goad him to fight me on battlefields of my choosing.
-I would create fake enemies and threats all around him so that he was afraid of every shadow.
I discovered the reason they played the strategy game... Was it because they enjoyed fighting? If so I'd suck all the joy out of fighting. Was it for a sense of accomplishment? If so, I would wastefully burn their accomplishments to ashes. I anihilated them.
Not only in the game... but also emotionally.
You do not want to become an "Evil" person in the eyes of an INFJ... Trust me.