Peacekeepers should be armed with heavy weapons and allowed to use weapons when they wish. Two fighting sides should be afraid of them.
I am not sure this would do anything to enforce the peace.
A conception of armed neutrality has a very long history... Its effectiveness was proven many times. The most recent example is enforcing peace between Pridnestrovian Moldavian Republic and the rest of Moldova through placing the troops between two warring parties. 20+ years have passed since that time without any shots or deaths.
P.S. And at least they won't get killed or trapped.
I understand your point, but I am not sure about the "heavy" part when you say "heavy weapons"....my initial reaction to what this would be is something along the lines of tanks, RPGs and similar weapons designed for serious warfare. I agree they should be armed, I am just now sure what exactly they should be armed with.