Simple question : Does the xp bonus is also given to the leader ?

Damn nice skill if it does.
Anyone can confirm this ?

If you save your game kill a stack of mobs see how much exp you recieve, then load the game and pick weapon master and kill the same stack of mobs, you will beable to tell if it effects your leader or not. I'm fairly sure it does. Just make sure its a fairly good stack as you wont beable to tell from something like goblins very well.
Just remember that it wont stack with tome of war so if you have that already don't bother with weapon master.