Hamedo is a reaction ability. The Monk class learns it for 1,200 JP (or 1300 JP in the PSP version). It functions like Counter; however, rather than attacking after being hit, the unit using First Strike attacks the enemy preemptively and cancels the enemy's hit.
The ability's success rate is affected by the character's Bravery level and will work against all uses of the Attackcommand by units in the character's attack range. Unfortunately, this means that monster abilities will not trigger First Strike unless they are under Frog status, but ranged strikes will, if the character is equipped with a similar weapon.