Heirloom 武器選び

Death Knight: no weapon needed
Druid: no weapon needed

Hunter: Heirloom Bow, and can use Heirloom Sword/Dagger as a stat-stick

Mage: Heirloom Staff
Priest: Heirloom Staff

Paladin: Heirloom Axe
Warrior: Heirloom Axe
Shaman: Heirloom Axe*

Rogue: Heirloom Sword/Dagger

Warlock: Heirloom Staff

*This is another sticking point. The Axe is definitely your weapon of choice until level 40 when you get the dual-wielding talent. I'm not experienced enough with a Shaman to conclude if the Axe's DPS makes it better than DWing with quested weapons, but either way it's not going to impact the number of Heirloom weapons you'll have to get if you're already getting the Axe for the Paladin and the Warrior anyway.

That being said, the Shaman is probably also a case of the Feral, in that Enhancement is still faster than Elemental even if you don't use the Axe.