In DDv4, Gargoyles (and other monsters who are unharmed by "normal weapons") are vulnerable to the attacks of Heroes & Super-Heroes wielding otherwise-Normal weapons.
Gargoyles appear much as the sculptural depictions in gothic architecture. [...] They are fond of ambush and normal weapons do them no harm.
(emphasis mine)Normal-Weapons are all non-magical arms including swords, spears, axes, and maces wielded by normal man-types. An otherwise normal weapon wielded by a heroic/superheroic-type is considered heroic.
This is not present in OD&D, where it is very clear (complete with an underline):
(from the monster listing in Book II)Only magical weapons/attacks affect Gargoyles.
Given that (presumably) we're currently up against a gargoyle, may I ask which way you'll be ruling on this? or shall we find out via experimentation?