Some builds I have no luck with; can never win with warrior or charmer (though that may be a me problem)
Bro Charmer is the single biggest damage dealer this game has to offer like what you talking about?
Honeslty I tend to have the most power playing as either a Charmer or a Black Mage but the game can be beaten basically with any class if you do the honored, age-old tradition on this game's character build, that being:
1) Always Go for one good AoE damaging/healing skill, this game loves those who use AoE (Bolstering Dance/Allure/Fireball/Group Heal/etc)
2) Don't give a fuck about fashion just grab whatever increases your main stat (Sexyness/Magic Power/Attack Power) for each slot & if you can't do this then grab the one that grants you a nice buff or that best increase your overall defences (Mare's Ring is a must-have for Warriors, having extra HP and a passive HP regen is hella good!)
3) IF you have high presence then your Encounter Power should ALWAYS be summons, prefferably those with AoEs of their own to further honor rule 1, Summons such as: Fire Dancer, Cassidy, Grungendyr, Lust Elemental, etc all of those are great and will deal damage constantly REGARDLESS of what happens to your character (it's nice to have a damage source when Stunned/Knocked Prone)
IMO The Prencese stat is WHY the Charmer, Black Mage & White Mage are considered the KINGS in this game, not only it powers your summons like crazy (My boi Grungendyr has 156 attack power) but it ALSO powers up your companions so basically so if anyone is struggling I REALLY suggest them to try out any of these 3, they DO go the distance.