Absorb Damage

From FFXI Wiki

Since Nocturnus Helm and Nocturnus Mail there have been several items and Atma added to the game that permit the absorption of damage, along with Paladin's Creed Set +2.

When Damage absorption procs, you gain HP equal to the amount of damage you would have taken with no -% Damage Taken equipment of any kind, Shell, or Phalanx.

References

Nocturnus Helm testing (Kirschy, BG)
Further Absorb Testing (Byrth, BG)