Hm... I have some nice ideas for my dancer.

Maybe a "rogue/support"
Flexibility and agility coupled with acrobatics give her high mobility.
Her unique weapon strike targets with nasty wounds, inflicting bleed and being particularly hard to avoid due to the complex dance used to wield it.
Her dances can apply debuffs or buffs to enemies and allies.

Overall it's a really squishy class centered on using her mobility to take down strategic targets and apply buffs and debuffs, without suffering from the mobility issues from more "traditional" support classes