WowAce

Several races have weapon type-specific racial bonuses that provide buffs such as crit or expertise when that type of weapon is used.  It then only logically makes sense that gain or loss of these racial bonuses when comparing weapons were to be calculated.

For instance, humans gain 3 expertise for using swords or maces, but would lose that expertise if they used an axe instead.
Dwarves gain 1% critical strike chance with Guns, but would lose that racial crit if they used a bow or crossbow.
(I know this is an Alliance-centric set of examples, but I'm not familiar with Horde racials.  I do know they have some weapon related ones)