In "Cephelia," the Black Iron Halberd is a highly effective greatsword-type weapon. It is an upgraded version of the Allergy weapon, with a special effect that expands the range of the special attack whirlwind. When dealing damage to outer circles, it inflicts an additional 50% damage and restores HP equal to 0.7% of the damage dealt to the outer circles.
How to Play with Cephelia's Black Iron Halberd
I feel like its built-in sustainability is just too strong. In multiplayer, if you don't want to think too much or are carrying new players, you can just stick with Fortify Guard to stubbornly stay alive, leaving the DPS to your teammates. Your job is just to hold your ground and revive fallen allies. There's a certain beauty to playing without having to use your brain (though you can't spec into boss lifesteal).
The black circle in the video is the effect of the Absolute Ring.