The Coalition has multiple biological based weaponry. When it comes down to actual viral/bacterial based warfare the Coalition uses it's super-advanced VICNI technology, nanites that can be programmed to infect certain life-forms, do certain things, and can be equipped with many other technologies for dangerous combinations. Such as Nilgaitt VICNI, a dangerous robotic pathogen that is immune to magic, or a Basilisk VICNI, an airborne pathogen that causes all organic beings it comes into contact with to turn into stone.
Another biological weapon the Coalition uses would be the Locust armor, the special forces of the GRASS division. It uses genetically modified Lorcar DNA to allow the user to perform feats only known by Lorcar PYSKERS, as it is also infused with assassin DNA it is immune to the King's psychic command.