It's interesting that a steel warhammer does far more damage than a platinum warhammer of the same size--the platinum hammer would be far heavier.
Then again, it might be the case that a dwarf of fixed strength can swing a heavier weapon like that with less force, averaging it out to mean that materials of different density result in constant damage, and that it's the relative HARDNESS of a material that describes how quick the blow is, meaning gold would make a poorer warhammer than steel since part of the impact would be soaked up by the weapon itself deforming.
Still, I have a hard time visualizing an adamantine warhammer being of as much use as advertised, since there's got to be some threshold where a dwarf has a maximum speed he/she can swing a weapon, and light-as-a-feather adamantine would be beyond that cap and therefore LESS valuable as a weighty weapon.
But as sharpened pointies it'd of course be first-rate. Heck, the extracted threads might lend themselves to different weapon designs. Imagine an axe that, instead of having a full metal head, was just a triangular frame across which was stretched a wire of unimaginable strength and tension, finer than a hair and able to quickly slice enemies apart. "Cheese Slicer the Decapitator of Nobles, an *adamantine wire axe*. All craftsdwarfship is of the highest quality."