Weapon master advantage and modified weapons?

[faitfull]

Hi

first of all, thanks for all the help I have gotten again and again in here. Love you guys and girls.

The Weapon Master advantage (b99) with 2 weapons says:

Two weapons normally used
together. Examples: broadsword and
shield, rapier and main-gauche. 25
points.

I am in a fantasy campain, and I have (throwing axe and Large shield) (not sure if this is correctly made by the rules)

however given that my character is a dwarf that have crafting skills and sometimes work like a smith, I plan to make the axe a axe with a hammerhead on the other side of the stick. Sometimes skeletons are a problem after all.
so acording to LT companion 2 page 14:

Hammer Head
A swung, hafted cutting or impaling weapon can have a
hammer head behind its striking head. Damage is that of its
usual swinging attack, but crushing. Base cost is +$25.
Weight is +0.5 lb. Applicability: Swung, hafted cutting or
impaling weapons.

So all in all, does my weapon master also cover the attack with the hammerhead? or do i need to extend my weapon master to a higher class like (dwarven weapons) and add something in here with my GMs permission?