Weapons, and weapon trees, I wish would be added in some way:
Unarmed:
Skills could focus on interrupts; stuns, and knockdowns with haymakers, trips and the like.
Bo Staff:
Skills could focus on slowing attackers skills that strike to the arms, legs, and head.
Throwing Knives:
Work kind of like bow & arrow, only you're throwing knives instead of shooting arrows. Think of it like the 'Two Weapon' of ranged attack, whereas bows are the '2-handed' ranged weapon.
Skills focus on rapid DPS, same was wielding 2 weapons; flurry of thrown knives instead of stabs. Skills that rapidly move the character left or right or back with attacks worked in, to avoid area of effect attacks.
There's others I want, but they fit into already-existing skill trees:
Spears (2-handed with different animations)
Crossbows (Just a slower, stronger bow & arrow, really)
etc