With this datapack, you can now upgrade your golden sword!
It will be done by throwing materials together on the floor.
Since copper is one of the most useless materials, the upgrades are mainly done with copper.
If you found any bugs or have any advice, please leave a comment below!
A diamond will be appreciated!

You will need: your sword, copper blocks, and other resources.

Unbreaking V: sword + copper block + iron ingot
Unbreaking X: sword + copper block + iron block
Totally unbreakable: sword + copper block + obsidian
Repairing the sword: sword + copper block + gold block

Fire Aspect V: sword + copper block + fire charge
Fire Aspect X: sword + copper block + blaze rod
Sharpness V: sword + copper block + anvil
Sharpness X: sword + copper block + diamond

Notice: Higher level of enchantments is available only if the lower level is already there.

Here, you can craft a knowledge book with 8 copper blocks and 1 iron block.
When you enter the nether portal with the book in your hand, you'll be teleported to a castle (mainly made by bedrock & black stone) over the lava sea. After finishing a parkour, you will see 4 chests with some valuable resources.
To go back, go into the nether portal bounded by bedrocks with the book in your hand.

Notice: Here the coordinates are scaled by 20, i.e. one block here = 20 blocks in overworld.

In the new dimension, you can find a chest with enchanted copper ingots. They are really important!
Again by throwing the materials together, you can make your golden sword more powerful!

Lightning: sword + magic ingot + amethyst shard
Press "F" to trigger. When triggered, it launches a trident with no gravity that will explode when hitting entities or blocks, but also gives you 2 seconds of wither. Has a cooldown of 1.5 seconds.

Critical Hit: sword + magic ingot + emerald
Your attack deals extra damage to all entities around you every 3 attacks.

Bloodlust: sword + magic ingot + golden apple
You will regenerate health and have some positive effects after dealing damage rapidly.
You gain 2 points of hunger every 4 attacks.

Elytra:
You can craft an unbreakable elytra with 9 leathers and 1 magic ingot.
When equipped, looking downwards gives you jump boost (so that you can fly directly), and looking upwards when flying gives you levitation.

Enderdragon:
Since the player is too strong with everything above, I modified the endergragon a little. Now, its fireball causes more damage and generate an end crystal and a phantom after exploding.
If you stay on the ground, you'll be bombed by the fireball every 5 seconds. (Remember the elytra?)