You make interesting points! If it was a normal story it would not make much sense, but since we all basically find the Gjallarhorns out in the wild or buy them if available, I think that what you describe might already be a thing of the past. Afaik no one is "gifted" a Gjallarhorn anymore. I supposed the ones that were originally gifted are now strewn across the solar system to be picked up by lucky individuals, including hunters.