The UNSC heavy frigate was a Light-capital warship used by the United Nations Space Command Defense Force during their twenty-seven year-long war with the genocidal theocracy known as the Covenant.
History
Prior to the Insurrection of the late 25th century, the concept of a "heavy" frigate was considered a gross misuse of the UNSC's funding. In the years following the coup d'etat on Eridanus II and the rebels' capture of the Template:UNSCship, there was much more support for a shake-up of the UNSC's relatively lax and ill-defended fleet. These upgrades would take effect during the disasterous Operation: TREBUCHET.
Design
The heavy frigate was essentially a more heavily-armored variant of the standard UNSC Frigate, equipped with more deck guns to provide stronger support in battle situations.