No, no. My dear friend, Hercules killed many a beast with his bare hands before he became immortal. As a Demigod he was forced through the ten trials of Hercules, each featuring a mythical beast to kill, and the Greek armies did not have access to mine copper from Olympus willy-nilly as such you claim. 

In true mythology the requirement of a specific weapon is not as Camp Half-blood makes it, in true mythology the Copper of Olympus was used to imbue weapons with godly power. Examples are Perseus' Sword during his slaying of the Kraken, or the Brother's Three Spears. The Celestial Copper was simply a material to imbue weapons with power, not to make them capable of slaying greek beasts. 

In every form of the tale(except th Camp Half-blood one) Medusa is decapitated by a normal blade. Never is there a version in true mythology is there a variant in which they require a special one. 

What I am saying, to be blunt and quick, is that this Rp is based off Camp Half-Blood, but it's details, lore, and specifics of Greek Mythology come from, for the majority of everything, true Mythology.