The answer to this might be the fact that the raven familiars come with a Damage Reduction of 5/+1 similar to the Damage Reduction of a ghostly visage. Just bear in mind that the hp of familars is half of that of their summoners.

Feel free to correct me if I am wrong in this.

Zodiacspear (aka Timgood) 
Sothe (Master of the Crashing Wave monks.) Gerald (Rogue who thinks he's funny.)