[Quote=Camp Half-Blood Wiki]

Magical Metals (also called Blessed Metals) are metals that can be used by Greek and Roman Demigods andimmortals to fight against monsters and other evil creatures, as well as gods and other demigods. The Greek Gods and demigods use Celestial Bronze, while the Roman Gods and their children use Imperial Gold. Hades, those who live in the Underworld, and some of his children (like Nico di Angelo) use Stygian Iron. Demigods use weapons made of these metals, because these metals are the only materials by which a monster can be harmed.

Celestial Bronze:
Celestial BronzeCelestial Bronze is mined from Mount Olympus, then forged by the Cyclopes, tempered in the heart of Mount Etna, and cooled in the River Lethe. The metal does not harm mortals, considering them not important enough to injure, but is strong enough to cut through a steel door. It is also been mentioned that this metal glows when in weapon form. It can also be melted down to make other weapons, such as bullets, as seen in The Titan's Curse.

Imperial Gold:
Imperial GoldIvlivsIt is unknown where Imperial gold is mined from, but it is be consecrated it in the Temple of Jupiter on Capitoline Hill in Rome, as stated by Midas in The Lost Hero, and forged at the Temple of Jupiter at Camp Jupiter. The metal is extremely rare, but very powerful. It is also quite volatile. It is also thought that because of the blessing of Jupiter these weapons are more effective againstVenti. This metal is favored by Roman Demigods. Whether the Roman aspect of the Gods carry weapons made of Imperial Gold or Celestial Bronze is unknown.

Stygian Iron:
Stygian ironA metal rarer than both Celestial Bronze or Imperial Gold. It's forged in the Underworld and cooled in the River Styx. It is possible that only people or beings of the Underworld can wield this metal (Hades, his children, and other beings that live in or are associated with the Underworld). Where weapons made from the other Blessed Metals cause monsters to disintegrate, Stygian Iron absorbs their essence, causing them to either not being able to reform ever again or take a longer time to reform. Like Backbiter, it can also harm mortals. Like Celestial Bronze, it also gives off a faint light.

Silver:
Although silver is not regarded as a magical metal, it is the only known weapon able to harm lycanthropes.  It is also unknown whether Stygian Iron can also hurt them[/quote]

Okay this is about the silver weapon again. I looked into it and while silver does have certain properties such as being able to kill a werewolf were celestial bronze cannot it is not actually capable of killing a greek monster. The hunters of Artimas use silver to wound monsters during the hunt so they may capture them and remove trophies before killing them with celestial bronze knives. Silver weapons while capable of harming greek creatures can't actually kill them.