While the Angelic Mantle gives significant resistance bonuses to fire resistance when wearing enough set pieces, the rest of its stats are mediocre at best. There are better armors for resistance past the early-mid game.
In the early game, however, the Angelic Mantle is a powerful item, particularly when mixed with the Angelic Halo and/or Angelic Wings. Its defense is one of the highest for a body armor piece at the level it can be worn, and the ring and amulet both have substantial partial set bonuses.
Defense: 68 (Base Defense: 45-48)
Defense: 218 (Base Defense: 45-48)
Required Level: 12
Required Strength: 36
+40% Enhanced Defense
Damage Reduced by 3
+150 Defense (2 Set Items)
Fire Resist +50% (3 Set Items)