Weightstone

A consumable item that adds an imbue to a Blunt weapon that temporarily increases Weapon damage and some also increase Critical strike. Most are created with Blacksmithing. As of Patch 2.3, weightstones last 1 hour.

As of Patch 3.0, weightstones can no longer be used on any weapon whose Item Level is higher than 165.

Additional info:
 * Sharpening stone - a Edged weapon imbue (or enhancement) that temporarily increases Weapon damage.