Indestructible (Effects that say "destroy" don't destroy this artifact.)
Equipped creature gets +2/+0.
7/1/2013 Darksteel Axe itself has indestructible, not the creature it’s equipping.
7/1/2013 Although Darksteel Axe has indestructible, it can still be put into the graveyard for other reasons. The most likely reason is if it’s sacrificed.