The addon can be found here: http://te4.org/games/addons/tome/archer-damage-info.
This addon displays more onscreen information about the damage your bow/sling does. It gives the standard damage, plus the crit damage, and then the average damage, taking both into account. This is damage per *hit*. It also provides a damage per *turn* average, taking into account attack speed. This addon was developed in light of the discussion in http://forums.te4.org/viewtopic.php?f=41&t=33873 or the advantages of Rapid Shot vs Aim, and the effects various modifiers have on damage.
The addon accounts for damage modifiers, crit damage multiplier, attack speed, and the usual stats for damage.
What is can't account for is factors other than the weapon, such as enemy armour, enemy resistances, and your resistance penetration.
So it is also useful for determining the better damage from two or more different weapons, which makes it extremely interesting!
Enjoy !!!!!!!!!!!!!!!!!!!!!!!
