The script works for me, as long as I
a) Comment out this line:
party.berserkerScript.weaponUnequip(self,champion,slot)
b) Change this line:
requirements = { "critical", 2, "epic_weapons", 3 },
to
requirements = { "critical", 2 },
c) Change this line:
spell = "darkburst",
to
spell = "fireburst",
The power attack works until it runs out of charges.