Somehow the meteoric iron has a higher carbon content, turning it into steel in a setting without any.
Inverted: Only suckers use swords made from meteoric iron; stainless steel is way better.
Subverted: The hero gets a sword. He's told that it has magical powers because it comes from the sky, but it's actually a Magic Feather that's no better than any other random sword.
Double Subverted: The hero gets a sword. He's told that it has magical powers because it comes from the sky, but later learns that it's actually a Magic Feather that's no more magical than any other random sword. After putting it aside in disgust, he realizes that its capability to hold an edge is exceptional (though nonmagical).
Parodied: The best swords come from the Isle of Skye.
Zig Zagged: The hero gets a sword. He's told that it has magical powers because it comes from the sky, but later learns that it's actually a Magic Feather that's no more magical than any other random sword. He's inspired by the story to make his own magic sword out of meteoric iron, but later learns that any random iron would have worked just as well for the spell he developed.
Averted: There are no meteoric-metal swords in the story.
Enforced: "Guy with sword has been done before, it's boring. I need ideas. "Sky Sword!!!!"
Lampshaded: "He's got a meteoric-iron sword?! Everybody run!"
Invoked: When given a choice, the hero ventures far and wide in search of meteoric iron for his new sword.
Defied: "A meteorite crashed? Better blow it up so nobody can take the metal and forge it into some awesome sword or something."
Discussed: "Don't you remember? The most expensive weapons to buy are the ones made from meteoric-metal, and that's because they're really powerful!"
Conversed: "The main character always has a special sword. Being made from a meteorite's pretty popular, supposed to make it better or something."
The scarcity of meteorite metal renders the awesome weapons too valuable to actually use for fear of losing or damaging them, so they're basically just museum pieces.
Thunderbolt Iron is actually merely magnetic, and it was called magic by a people who didn't know what magnetism was.
Their ignorance of modern chemistry that we take for granted lead them to miss that Thunderbolt Iron also happens to contain some impurities... some radioactive impurities.
...Then, in need of a really good weapon, the hero raids the museum and uses one of the priceless weapons anyway.
The enemies in the series are disoriented or wiped out by sufficiently strong magnetic fields.