A large, steel, warhammer, slightly bigger than is common. The head is engraved with dwarven runes of magic and power - it is clear upon looking at it that this is a weapon of might.
Long ago, the dwarfs of Thodar were beset upon all sides by enemies. Not only did they have to defend themselves from orcs, monsters and other forces of evil but the wealth of their underground kingdom excited much jealousy amongst the neighbouring elven and human kingdoms. Though valiant in battle, the endless warfare on their borders began to take its toll - not only in life, but also in spirit.
In such a time, the craft of the warrior became esteemed above all other crafts; prowess in battle was the epitome of greatness. And thus it was that the dwarfs of Thodar decided to forge a weapon that was not only mighty in its own right, but could shape and mould the wielder in to a greater warrior.
Upon picking up the Warhammer of Thodar, the character who picked it up will feel magic rushing through his body, changing him and reshaping him. This influx of magic will hold the character stationary and helpless for five minutes, though his grip will tighten on the handle, meaning he won’t drop the warhammer. The character receives a significant permanent drop in intelligence and wisdom and will lose/become worse in some skills (combat skills are never affected). If the character can cast magic, his skills in this will also be somewhat impaired. He will also gain a major increase in will (by will I mean resistance to fear and similar things) and a minor increase in hardiness (i.e. increase in hit points or similar). These changes are permanent and will not go away if he puts down the warhammer.
The warhammer itself is significantly better than a normal warhammer, both in accuracy of hitting and damage done. It can also harm magical creatures, occasionally split shields (depending on the strength of the wielder) and, if the wielder is quick enough in reactions, can or partially block some spells such as fireballs, lightning bolts.
The ability gains and losses should be such that, for a dedicated warrior type, it is definitely worth the price (providing you are going to keep using the hammer).
However, they should also be such that if you are not planning to keep using it, the losses are not worth the gain even if you are a straight fighter (i.e. this is not a weapon you use for a few days while your friend is wounded).
If a non-dwarf picks up the warhammer, he will receive the ability losses but not the ability gains. The weapon will also react badly to the touch of a non-dwarf, making it much less accurate in combat causing it to try to twist out of your hands when you use it. This will not be apparent until you are actually in combat.