A player of mine use a spell with a Enchantment that target a weapon of another player. When the other player tried to enchant his weapon, he couldn't do it and the error bellow was showed.

Makes no sense that only the GM can apply enchantment on items that was not from his features. There's a lot of spells that a player can enchant other players items and with this, the GM has always to manually enchant everyones items.