Omen of Whittling IS WAY TOO CONFUSING

I have a gigastaff and i bought a whittling omen to roll away my lowest level roll / lowest roll with the lowest requirement which is a low roll of fire damage.

Looking at PoE2 DB i'm extremely scared to use it because i'm not even sure if it works the way i think it works.

If someone wants to help me out.

Item Class: Quarterstaves
Rarity: Rare
Brimstone Pillar
Expert Barrier Quarterstaff
--------
Quality: +20% (augmented)
Physical Damage: 355-604 (augmented)
Fire Damage: 13-25 (augmented)
Critical Hit Chance: 10.00%
Attacks per Second: 1.65 (augmented)
--------
Requirements:
Level: 79
Dex: 165
Int: 64
--------
Sockets: S S
--------
Item Level: 79
--------
40% increased Physical Damage (rune)
--------
+13% to Block chance (implicit)
--------
156% increased Physical Damage
Adds 42 to 73 Physical Damage
Adds 13 to 25 Fire Damage
+27% to Critical Damage Bonus
18% increased Attack Speed
Leeches 6.32% of Physical Damage as Mana