The fighter can be split into two general types, the Shockwaver and the Buffer. Shockwavers rely on the Shock Wave skill to attack crowds of monsters, and are popular damage dealers. Buffers control some of the game's most powerful Buff spells, and are essential to successful parties.
As mentioned before, Shockwavers rely on the Shock Wave skill to attack mobs. By rounding up a crowd of monsters, the Shockwaver can attack several enemies at once, speeding up the killing process. Also, Shockwavers benefit from the added damage that Shock Wave provides to their base damage.
Buffers in Cronous are akin to healers and white mages in other MMORPGs. Buffers command a healing spell, Minor Healing, to keep all party members healthy. Buffers also use Life Up and Holy Armor to raise party HP and Defense respectively. These spells are incredibly useful to high-damage, low-defense classes like Valkyrie and Mage.