The polaron pulse rifle, also known as a phased polaron beam rifle, was the standard and primary weapon that was employed by the Jem'Hadar.
History and specifications
It was capable of firing an energy 'shell' that could damage enemies around the target which made it excellent in killing groups of enemy infantry.
A secondary fire mode allowed it to 'poison' the target with an anti-coagulent which prevented the body from healing and made the enemy literally bleed to death. (DS9 video game: The Fallen; ST reference: The Visual Dictionary)