The more you prestige the better tier it becomes:
Prestige 1 - Stone
Prestige 2 - Copper
Prestige 3 - Gold
Prestige 4 - Iron
Prestige 5 - Diamond
Max Prestige 5 - Netherite
In my opinion this is a great idea! I love the idea of having just one extra item to throw on top of what you get at the moment; because right now it’s not much. As for like for other items no but as long as we only get this item sure. I do suggest changes to the way they are awarded though-
Stone- Lvl 100
Iron- prestige 1
Gold - prestige 2
Diamond - prestige 3
Emerald - prestige 4
Netherite - prestige 5
And if you are lvl 100 all the spears get an enchanted look.