After hanging out with some ghosts (0 armor) the following seems apparent:
2 hunting levels = 1 damage.
5 weapon skill levels = 1 damage.
Damage range is ±15%.
My stats were 121 hunting, 70 dagger and 48 damage.
This would predict: (120/2)+(70/5)+48=122 damage.
122±15% would be a damage range of 104 to 140.
My hits were between 104 and 139.
—
Compared to a pickaxe on sheep (which have 3 armor, but for a rough comparison):
My stats were 121 hunting, 29 pickaxe, and 37 damage.
This would predict: (120/2)+(25/5)+37=102 damage.
102±15% would be a damage range of 87 to 117 before armor.
My hits were between 84 and 112, which would seem consistent for 3 armor.
Hopefully this lines up with what others experience.
Cheers!