01. The crystal no longer resides inside Cain. He hurled it into space, yet somehow retains the power.
02. Both Wolverine and Sabertooth are listed as having a durability of 4, and that takes the Adamantium into account. So I have to guess that it either breaks or the metal deflects off the impenetrable hide. Also remember that Captain America's shield (made of Adamantium and Vibranium) has been shattered. Even after it was fixed, it has since been dented and reshaped by Thor. Granted, his shield isn't pure Adamantium, but it goes to show that Adamantium can be damaged.
With all this back and forth, why are their only two votes?