Weapon Level

Having seen a bunch of boss fights where someone's fighting endgame bosses at level 1 with a level 1 starting weapon has made me wonder: If we can select the tier of the weapon, from Common - Legendary, why can we not forge weapons between level 1 to the highest available level we can forge?

I understand that it's a silly thing to want since it'd only appeal to people who want to do such self imposed challenges, but the option would be nice for those that would do it. I'm doing a fresh save file for a spear playthrough anyway, but just having that aforementioned option would be nice because then you'd have a level 1 spear or greatsword as well, not just dual wield, for those that want to use other weapons that aren't dual wield.