Blade of Banishment:

While Bullets of Banishment exist, they are very expensive and literally one-shot magic items. Some elite snipers use them, and it is said that the matching pair of .50 caliber ivory-handled revolvers worn by General Nyssim are loaded with them.

But even for elite combat units, the cost to manufacture such bullets is prohibitive.

A slightly more expensive but infinitely reusable Blade of Banishment is one answer. Although only fielded by elite Assault and Guard units, these weapons are greatly feared by the demon hordes.

Their first use came in the Battle of Taiabar Hill. When the order to fix bayonets was shouted out, the demons laughed and charged en-masse. The first wave of demons was destroyed and the second decimated before the demon commanders were aware of anything. When the second wave faltered and retreated the mortals attacked, driving a wedge right into the headquarters of the demon army and slaying its leadership. The battle became a route as demons fled in all directions.

In the aftermath of this battle the leaders, banished from the mortal realm for a century, were then subjected to displacement from their positions of power in the demon realm as rivals usurped their commands.