The entire S&H tree, the Bows, 2handed, even Dual Wield could use a good doubling of the damage of all the trees.
and thats just for starters across the board.. some need alot more than others.
At the moment most Weapon skills are just too weak to be useful compaired to class abilitys, the stamina ones in particular are generally not worth using.
a good example... I can hit 1k Damage per second on my Sorcerer using Class abilitys in rotation.
But the same character shifted from MP to SP can at best hold 300dps by spamming Flurry on a single target(assuming most hits crit)
the small number of really useful Weapon skills are usually useful because of their added effects, like the 3 second immobilize on Bombard IV. Or the Taunt effect of Puncture(the debuff on this is nice tho).
in some ways, this is the most pressing issue in terms of balance in this game. Attacking with your weapons is generally less than 30% efficient than attacking with class ability (even NB does better relying on class spam for good damage)
I play every class in every situation. I love them all.