The duelist abilities previously had much, much higher bonus damage, it got nerfed.
If you find a ranged weapon early game becomes simple on duelist, its easy to get things into kill range of disengage. If you don't, disengage 2 is still very good at kiting back from fights. Disengage/step back lets you move pretty far, using the terrain to your advantage. A key thing against frogs is to use unstable terrain to get the kills to keep your SP. Sometimes, taking a hit to use a normal attack is worth it, to bring them into kill range for disengage.
Yeah, that's what I like about this game - it goes from impossible to 100% win rate all depending on player skill, not grinding some levels.