There is another interesting explanation for adamantine.
A material as dense as slade would fold space-time and create significant amounts of micro-singularities in the proximity of such slade. Micro-singularities would distort materials into exotic forms that would normally be impossible as following standard physics. Indeed, adamantine's unusual molecular properties attest to this; only in the absence of physics would they be possible. Adamantine's lack of conductivity would not deprive it of thermal energy; rather, it would merely maintain the thermal level of the environment in which it was created. This explains the ripple effect exerted by adamantine edges; it is, indeed, thermal imbalances that are being observed in the presence of kinetic motion and the friction that is inherent therein. ***LIGHTSABER***
Adamantine is workable by dwarves because dwarves are actually capable of psionic molecular compression and decompression. It is why they are able to mine so quickly, and smith in the absence of most necessary tools. Dwarven master crafters/miners are those that have trained their psychic abilities in the manipulation of certain materials, and can thus effectively distort them more effectively in the extant of their chosen fields. Dwarven martial trances are extensions of this, as applied to combat; they achieve states of supreme meditation, and thus excel temporarily in the usage of the psionic distortion fields as applied to combat. Booze is the primary catalyst of dwarven psionics; they use its hallucinogenic effects as a focus for their powers, and have developed addiction of various degrees to it. Dwarves that do not have access to alcohol become less productive, as is to be expected with the lack of a psionic focus (and withdrawal). To get back on topic, though; dwarves use these abilities to manipulate virtually any material (except slade, because it's extreme density renders it beyond the capability of manipulation). It is why they alone are capable of utilising adamantine; they temporarily "bend" it on the quantum level to a state that they can mine and use, before it reverts back to its normal (and impossible) state.
The psionic dwarves theory also explains the unusual dynamics of artifacts and their creation.
In fact, psionics makes too much sense in an incredible synapse of many normally impossible actions that are observed in DF.
But if you get the gist of what I'm saying; yes, dwarves that wield adamantine are medieval Jedi.