Path of fury states that they get a more effective weapon block. Now, this does not translate into percentages, so what does it mean? Do you have to be raged to get it? How much more effective?
Berzerker Weapon Block
dunno, wish I could be of more help.
Weapon block has a specific circumstance that must be employed.
One of the conditions is that you wield a weapon in 2 hands. 
About the % i would say about the same you gain from being a Ogre over being a human give or take 1-3% for error margin. 
Bottom line, if he is dualing magic whips do not count on that bonus to save you.
In all honesty, path of fury is sooooo weak. You are better off going with either of the other ones in my descision.
Just my luck to pick the one that sucks, but I guess I'll stick with it anyway, as I'm already trained decently and I don't feel like starting over.
Its not that bad, you get more hit/dam and hp than anger, you have a small chance to relax and if you dont know where to find cursed weapons you wont be disarmed to the ground all the time which can make a difference
Yes, you can have a certain Heavy Magic Polearm socket cursed, with that i think you would never need to use another weapons, with the exception of dual unknown vuln weapons.
Also powergrip has a perk that you will never find out, if i recall correctly.
fury is good for giants, makes up for that low dex a bit with the improve block