Heavy Guard appears as a defensive ability. It has ATB costs of 15 (Lv.1), 14 (Lv.2), and 13 (Lv.3). It increases Lightning's physical and magic resistances by 50%. It is an upgraded form of Guard. It's effects can be buffed if it is used while wearing the Sacred Knight garb.
Heavy Guard Lv. 2 is a locked ability for Quiet Guardian and Heavy Guard Lv. 3 is a locked ability for Paladin.