The hard staff is simply a staff reinforced with metal heads. It uses the Spear skill to determine damage, and can inflict slightly more potent Blunt strikes than a normal staff. This weapon's defense bonus is significant. Not good for use as a solo hunter, but the hard staff is an effective weapon for blocking and counterstriking while your dogs tear your enemy apart.
URW Game Encyclopedia description
The official URW in-game encyclopedia (accessed by the key) describes the hard staff thusly:
A wooden staff reinforced with metal heads.