The coordinating enchantment on the mace "Ravenwing" is supposed to give +4 to accuracy and 1.25x damage when attacking the same target as an ally. However, when I used Ravenwing I didn't notice any increase in damage when attacking with an ally.
Looking through the comabt logs, I found that although the accuracy bonus is applied, there was no difference in the minimum or maximum damage (I tested about 20 hits under each condition). I also tested the crossbow "Good Friend", which also has the coordinating enchantment" and found the same results.
Is this a bug or is the item description just inaccurate?