The offender offends because he wants to gain something. His intent is to hurt, use, control, and offend so that in some way he comes out on top, to seemingly better his situation. He believes the offense will give him the glory he seeks. He may want to feel better about himself, superior to another, more powerful, or to gain position, leverage and control. When the offended reacts, attempts to defend himself or to vindicate himself the offender knows he has accomplished he desired outcome. He expects and wants a reaction. He has mastered you. This feeds into his desire for greater glory.
A wise man can snatch the glory from his hands through patience and mercy. "A man's wisdom gives him patience; it is to his glory to overlook an offense" (19:11). Where is the glory in overlooking an offense? Patience and mercy demonstrates your faith in God. You believe in God's ultimate justice and vindication. Your patience and mercy demonstrates your belief that God is present, he knows your situation and is powerful enough to deal with it in his time. When you are patient and overlook an offense you are taking the control away from the offender and putting God in control. And when we shift the glory to God, he allows the glory-giver to share in his glory.
Though righteousness has a price, it also has a reward. The righteous who show mercy can anticipate a future reward that is certainly more glorious than immediate vindication or justice on this earth. "Blessed are you when people insult you, persecute you and falsely say all kinds of evil against you because of me. Rejoice and be glad, because great is your reward in heaven..." (Matt. 5:11-12). Overlooking an offense also has benefit in this life, "Blessed are the merciful, for they will be shown mercy" (5:7). When you are gracious to others who don't deserve mercy, people sit up and take notice for it is certainly not the norm. Your character and faith is gloriously displayed. Your mercy will beget mercy and your patience will be met with patience.
Go ahead, be a robber. Rob the glory from the offender and give it to God. Be patient; overlook the offense. God, who is most patient and merciful, will graciously share his glory with you.