There is one only defect in forgiving persons, and not another; that defect is that people take a forgiving person to be weak. That defect, however, should not be taken into consideration, for forgiveness is a great power. Forgiveness is a virtue of the weak, and an ornament of the strong. Forgiveness subdueth (all) in this world; what is there that forgiveness cannot achieve? What can a wicked person do unto him who carrieth the sabre of forgiveness in his hand?

In plain words: The only downside of forgiving is that people may think you are weak, but ignore that, because forgiveness is a great power. It is the strength of the weak and the beauty of the strong. A wicked person can do nothing to someone armed with forgiveness.