Divinity (synonymous with mana in this world) was greatly essential in combat because it enhanced physical abilities, empowers weapons, and levels the playing field against powerful foes like Wave Beasts, Dungeon Beasts or Players more powerful than others in strength or skill measurement.
Using numerous Moonlight and Twilight Regioners as an example, many Players possessed abstract Skills that may not directly aid in battle.
This was where Divinity came in as it allowed them to augment their bodies or weapons for greater impact. By channeling Divinity into their limbs, fighters can deliver stronger blows, move faster, and endure more damage, while imbuing weapons with Divinity enabled them to penetrate magical defenses or deal elemental damage.
This versatility made Divinity indispensable when facing opponents with natural advantages like sharp claws, dense hides, or immense strength.