Sacrifices use Death, although it has a low base chance of hitting. Even when not invoking Instant Death, the Death spell deals quite a bit of damage, regardless of having the Shell buff on or not. This can be a threat to low-HP characters like Hope. The Sacrifice's Anathema can inflict several status ailments. They also use Aerora.
Debuffs work quite well and help keep the Sacrifices under control, especially in larger groups. A Cherub's Crown or the upgraded Seraph's Crown can be equipped for protection against Death.
Aerora shouldn't be too much of a bother if the Vigilance buff is active, as this will prevent characters from getting knocked off their feet.
Sacrifices are a considerable source of gil at the game's end, as they are easy to defeat in comparison to stronger enemies, such as the Adamantoise. Sacrifices also appear in larger numbers, resulting in better drop chances.