Blue-posting Blizzard dancer Ommra has reported that World of Warcraft's Mongoose enchantment (no relation whatsoever to Halo 3's all-terrain vehicle) has been fixed. Some have reported that the haste effect of the enchantment had been reducing stats on the damage aspect. Right now, it should be ok care of their latest hot fix.

But why was the haste effect reducing damage in the first place, as roopa from the same WoW Forums thread asks? Well, to be honest, we're not really sure either. Eataimedshot gives a possible reason why though (and even he's not sure too):

It's probably the fact that haste effects reduce the speed of a weapon so it's nothing using the usual weapons speed in the formula for counting the dmg done instead it uses the speed when its under the haste effect.