Specifically, the fact that it reduces weapon damage by 2. It does not specify melee damage, which is where my problem is.
It sets the precedent that physical inability can reduce a ranged weapon's damage, while the opposite (that extraordinary ability, or high Dexterity, can increase the damage) isn't true.
I would suggest that Sickened be altered to specify that melee weapon damage is reduced, but ranged damage is not.