Though your arguments may be convincing and believable, it is essential to prove to your listener why he should be convinced. Weighing and impacting strategies are critical to proving why arguments matter.
There are a variety of ways for you to weigh between arguments. Some ways of weighing impacts include:
Magnitude - How severe is the impact or size of the harm? If we're debating gun control, I might argue that restricting automatic weapons has a greater impact because it makes everyone safer. The impact is of a greater magnitude than, for example, the small number of people who want to own an automatic weapon.
Probability - How likely is the event? This focuses on things that are more likely to happen rather than those that are "worse". In the gun control example, you might argue that it's highly unlikely that you'll be victimized by an automatic weapon, but that restricting certain guns is definitely going to cause social unrest.
Reversibility - Can the harms be undone? If we lose a right or a privilege, that can be undone. If we lose 100 lives, they are gone forever. The irreparable harm caused by the loss of life from guns, you can argue, makes your impact stronger.
Timeframe - Is it a short-term or long-term harm? Will the harm come about now or later? (This is often used with statements like "We have time to fix the issue..."). Even if social unrest results from restricting the sale of automatic weapons, we have time to deal with that issue through legislation. The immediate issue is the loss of life from unrestricted guns.