EquipMisc

Any iron equipment can be upgraded to bronze to significantly increase its durability, putting it about halfway between iron and diamond durability.

This even applies to untiered iron equipment, such as shields and shears.

Bronze ingots can be acquired by smelting raw bronze, which can be crafted from 4 raw copper and 4 iron nuggets.

Bronze upgrade templates can be found in ocean ruins chests, and can be duplicatd with copper ingots.

Enchanted chainmail armor will be invisible when the player is under the invisibility effect.

Any (non-chainmail) piece of armor can be combined with a matching piece of chainmail armor to increase its armor and/or toughness points. This means you can wear lower-tier armor for aesthetic purposes and not have horrible defense.

Specifically, combining armor with chainmail will add two points to armor but capped at diamond level, and any remaining points get added to toughness instead.

Chainmail upgrade templates can be found in nether fortresses and duplicated with diamonds.

The turtle helmet now gives you 30 extra air bubbles instead of 10 seconds of water breathing. This means it compounds with the Respiration enchantment to give you at most an average of 4 minutes of underwater breathing.

Turtles can now be brushed to drop scutes. This uses 24 durability from the brush which means one brush lasts 3 scutes. Baby turtles growing up now drop 2-5 scutes.

I personally don't mind the midgame and I'm not too fussed about getting straight to diamond/netherite gear, especially since I don't find mining the most interesting. I think iron gear is fine for overworld combat & building, except for its durability, which is why bronze is just iron with better durability.

I wanted to give chainmail a use because it's weird how you can only get it from mob drops but it's worse than iron. I also think it's cool when people want to use armor for aesthetic purposes but it's often not feasible due to defense. I combined these ideas with the fact that IRL chainmail was worn beneath regular armor for more protection.

Making turtles brushable does mean skipping the turtle growing mechanic, but honestly I hardly see anyone grow turtles anyway so I don't think it's much of a loss. Nautiluses offer infinite water breathing so I think it's fair to make turtle helmets easier to get.