No, it is not a weapon, for it happens within one person.
The other does not need to even know about it and often does
not know about it. If he or she is told about it, that is a separate act,
coming after forgiveness; it is not a part of the act of forgiveness.
David, that seems more like a revenge than forgiveness from what you describe, no?
It does not necessarily require to get over resentment towards the offender. Forgiveness does not necessarily require one to get over the trauma caused by the offender but does require one to release resentment towards the offender.