What is Harry's Secret Weapon?

[Lydia French]

No: HPFGUIDX 167955

"The one with the power to vanquish the Dark Lord approaches. 
 Born to
those who have thrice defied him, born as the seventh month dies 
 and
the Dark Lord will mark him as his equal, but he will have power the
Dark Lord knows not 
 and either must die at the hand of the other for
neither can live while the other survives. 
 The one with the power to
vanquish the Dark Lord will be born as the seventh month dies. 
"

We know this means the power of Love but what does THAT mean?
Not just the protection his mother's loving sacrifice provided but the
power to FEEL love is definitely one explaination. It was his feelings
of Love for Sirius that forced LV out of Harry in OOP. However, as we
saw in GoF, in a one-on-one duel, Love is not a weapon Harry can wield
on his own. So, the question is, in what way is Love, this "power the
Dark Lord knows not" going to end up helping Harry in his battle with
Lord Voldemort?

Love,
firefly