In the distant past, armies in India often used elephants in battle. Trained war elephants were like living tanks, smashing through and breaking up enemy infantry formations. They were all the more deadly when equipped with tusk swords, such as this one owned by the Metropolitan Museum of Art in New York City. The 2-foot long blade would slip over an elephant's tusk, giving that already deadly natural weapon greater reach and piercing power. It's one of only 9 known to survive to this day.
-via The Soul is Bone