1. Enchanting Weapons
Weapon can be enchanted to offer a higher bonus to the character. Success leads to a % increase based on the material, but failure can lead to a 3% loss or even item destruction.
NPC - Blacksmith
Maximum Enchant - 120%
Enchanting Materials:
3% - Tin
6% - Dark Steel
9% - Black Steel
12% - Steel of Eternity
15% - Gold of Eternity

2. Weapon Combination
Another way of weapon improvement is combining weapons. Weapons that have the rarity Rare or Elite can be combined with other items of the same type and rarity.
NPC - Blacksmith

3. Weapon Crafting
Crafting consists of using multiple lower quality weapons to create an item of higher quality. Currently players have the option to combine a few different materials.
NPCs - Blacksmith - Enchanting Materials and Jades; Elder - Archives

4. Weapon Upgrade/Downgrade
12sky has the option to increase or decrease an weapon's level(12sky gold). This is handy if you have spent time, silver, and effort improving your equipment, or if you find a piece of equipment several levels too high for your character.
NPC: Beggar

Would you want to buy 12sky gold? Yea, we can offer to you if feel free at any time.