My take on the issue
This lot are taken from my manual of weapons, I never much careds for the view WOTC took on the issue of hammers. (Actually weapons in general) The warhammer is to my mind simply wrong, it does not fit with history and it certainly does not fit with fantasy. A Warhammer and a Maul are two completely different beasties. The Warhammer is a medieval device for opening up armour and the Maul was a peasant weapon all around the globe, look at braveheart, both are used in the film.
So here you go from Pole Hammers to Exotic Hammers the Gryphon way.
Bec de corbin
Also called the bec de faucon, the names mean “crow’s beak” and “falcon’s beak” respectively. This pole weapon has a hook much like a bird’s beak and is ideal for cutting open armor like some great can opener. The weapon also has a hammer or axe side that delivers a solid hit. This is a highly specialized weapon, designed for the purpose of cutting armor then striking the now unarmored victim with the other side of the weapon. The pole shaft is about 5 feet long.
Double Hammer
Two Hammers joined together by a wooden staff what could be simpler? It can be used as if it were two weapons and has all penalties for using two weapons if you decide to use it as two weapons.
Maul
The Maul is a two handed weapon, a huge sledge hammer on a long 5ft haft. It looks like a large version of the warhammer in the Core Rule Book 1. The maul was and still is a heavy wooden hammer or mallet like tool used to pound stakes into the ground. The maul, like many other domestic tools during the middle ages, doubled as a fighting weapon among the poorer classes of Europeans pressed into military service. By virtue of its size and weight, the maul required two hands to wield it.
Lucern hammer
The lucern hammer is a hammerhead with a spike at its rear, mounted on a long pole, reaching as much as ten feet in length. In some cases, the end is fitted with a spike to keep enemy soldiers at bay. It is one of the heavier pole weapons and is rather slow. The entire weapon is usually made of steel, including the pole, and often it is decorated with carvings and precious metal gilding.
The weapon has reach allowing the user to strike opponents 10 feet away but it can't be used against adjacent opponents.
When set to receive a charge this weapon does double damage
War Hammer
This weapon replaces the warhammer in the Core Rule Book 1, the Warhammer is a specific weapon designed in medieval Europe. The war hammer was a very specific adaptation of the blunt, crushing war hammer design we generally associate with the Norse deity Thor. The medieval war hammer was one of the few weapons with an edge that could both tear open armor plate as well as inflict devastating concussion blows. The war hammer usually had a beak-like blade opposite a faceted hammer, making it a combination of a mace and pick. The weight of the metal head concentrated on the sharp point of the beak after a full swing easily pierced both chain and plate mail. A spear-like tip on some versions allowed for thrusting as well as swinging. While some war hammers were of all metal construction, most were socketed metal heads attached to wooden hafts; metal reinforcement bars (termed langets or cheeks) along the side of the wood haft prevented the hammer head from breaking off during combat.
War Mallet
A single handed version of the Maul a heavy wooden hammer or mallet like tool used to pound stakes into the ground. During war, many mauls were reinforced with metal bands around the head to prevent splintering; many were also fitted with spikes on the striking surface of the head for increasing the damage they inflicted.
Simple Medium
War Mallet 8 1d8 x3 - 10 Bludgeoning
War Hammer 2 2d4 x2 - 6 Bludgeoning
Simple Large
Maul 15 1d10 x3 - 20 Bludgeoning
Martial Large
Bec de corbin© 8 1d8 x2 - 12 Piercing/Bludgeoning
Lucern hammer^ 7 2d4 x2 - 15 Piercing/Bludgeoning
Exotic Medium
Double Hammer¥ 8 1d4/1d4 x3 - 6 Bludgeoning
© Can be set to Recieve Charge
^ Reach Weapon
¥ Double Weapon
Editted cos I forgot the key