Perhaps a universal elemental buff as a basic 1-20 common skill for all classes. For 20-30 seconds your weapon and affected skills all do light, dark, fire or water damage. Some people may think this negates some classes' inherent element skills buy DFO gold as well as elemental weapons, but a skill with a long cooldown and fairly short duration couldn't compare to specialist elemental skills themselves as well as a permanent weapon with an element. With this in play, every class can take advantage of additional element + damage from magic seals as well as adapt to any dungeon without class based disadvantages (IE Soul Benders in a dark dungeon).
M/F Ranger ability; Retreating Fire (if you have a better name please say it lol). Description: Ranger leaps backward into a slide firing several precise shots at pursuing enemies, slowing their movement speed and dealing moderate damage. pressing cheap DFO Goldthe basic attack button repeatedly allows for more shots. Using this ability while dashing increases the distance of the slide. Collision with an enemy, object or ground effect, or being struck by an enemy attack will cancel this effect.