As an enhancement shaman, my main character has lost many a roll over the years to players rolling on weapons for which their class probably shouldn't even have been rolling in the first place. We enhancement folk are pretty picky about which weapons we'll use; slow one-handers with agility are the only ones that pique our interest (blasphemers who use spellpower weapons are dead to me), and only those of the mace, axe, or fist families. Back in Naxx, I lost out on Calamity's Grasp to a rogue who wasn't even specced into a fist weapon build. Hunters rolled on one-handed axes like Touch of Madness -- as if they couldn't use nearly every other kind of weapon! Even dual-wielding DKs tried to get their cold, dead hands on one-handers like the Lion's Maw.
If it were up to me, I would remedy this problem by creating a whole new weapon class: flails. Flails would only be usable by shaman (and maybe druids, because kitties are cute). Variations could include the medieval-esque spiked ball(s) chained to a short pole handle, or even the nunchaku style of two sticks chained together. The swiftly spinning ball and chain of death would fit well with the enhancement shaman's Windfury Weapon imbue as well.
If you could, what new type of weapon would you add to WoW? Which classes would be able to use the new weapon, and why?