I don't disagree with most of what you wrote, but I think it has to do with humility, not wisdom. Aragorn was so humble that he actually entered Minas Tirith in secret to heal those he could, but then left again and didn't claim his crown until he could do so without harming the alliance.
Denothor was not humble, and neither was Boromir. Both were full of themselves and their own power, as well as the power of Gondor. Farimir, on the other hand, was humble. Farimir also told Frodo that he would never handle "the thing" and then kept his promise once he discovered what "the thing" was.
Keep in mind that while most of our discussion touches on whether the men would use powerful objects, there is also the issue that Boromir had with the Stewards of Gondor continuing to wait for the King after so many generations. We are lead to believe that, had Boromir succeeded his father, he would have proclaimed himself king. That has nothing to do with objects of power.
So, was it wisdom or humility? Then again, can the two be completely divorced?
Shalom.
Not in my mind.