Blacksmith in C9 is very skillful. He not only can enhance weapons, armors and accessories, but is also able to repair them. Moreover, he also has a magic tool -- Blenheim Magic Cube, which can synthesize, refine and decompose equipment or other material.
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In C9, Mosaicist is an NPC who can socket equipment, inlay gems, magic stones or take them out of equipment.
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Enhance Equipment

By enhancement, your equipment can be upgraded to a higher enhancement level (weapons can be enhanced to +20 at most while armors and accessories can be enhanced up to +10). Every enhancement costs gold and the higher level you upgrade to, the more gold you have to spend.
In addition to gold, as the enhancement level rises, so does the risk. If you try to enhance a weapon of +9 or above, you have to bear the risk of losing it.
PS: The failure rate is different for different grade of equipment.
You can use some item to protect the equipment from disappearing during the enhancement procedure.
1. To enhance weapon, "enhancement stone" is required. It can be obtained by decomposing soul equipment in Blenheim Magic Cube or received from treasure chest.
2. To enhance armor, "enhancement component" is required. It can be obtained by synthesizing fragments with Metalworking function in the crating system or received from treasure box. [Check the Enhancement Materials]

Enhance Weapon:

There are two kinds of weapon enhancement stones. One is Magic Enchantment Stone, which is used to enhance weapon below Level 30 (but the weapon should be magical).The other one is Ancient Enhancement Stone, which can enhance weapon below Level 51(also should be magical weapon). The latter one can be synthesized by a certain amount of magic enchantment stones.
When a weapon of +9 or above is being enhanced, it may disappear upon failure.

Steps [Reference this steps when you come to Blacksmith]
Step 1: Find Blacksmith in the town.
Step 2: After popup dialog box, choose "Enhance Weapon"[武器强化], then switch to Enhance Weapon Interface.
Step 3: Pick the weapon you want to enhance from the pack, then drag it to the left slot, put the enhancement stone in the right slot, click the "Enhance" button.

Enhance Armor:

Armor enhancement component can be classified into three grades: elementary, advanced and superior. Elementary component is used to enhance armor below Level 30 (but armor should be magical).The second one is used to enhance armor below Level 51 and the third one is to enhance armor below Level 70 (both should be magical armor).
Enhancement component can be synthesized from fragments by Craftsman while fragment is obtained by discomposing equipment.
When an accessory of +4 or above is being enhanced, it may disappear upon failure.

Enhance Accessory:

In order to enhance accessory, two kinds of items are needed: pure crystal and unknown crystal. Pure crystal is used to enhance accessory below Level 30 (but accessory should be magical) while unknown crystal is used to enhance accessory below Level 51 (also should be magical accessory).
Unknown crystal can be synthesized by a certain amount of pure crystals in Blenheim Magic Cube[布莱尼姆魔方].
When an accessory of +3 or above is being enhanced, it may disappear upon failure.

Blenheim Magic Cube: refine, synthesize and decompose

The Blenheim Magic Cube contains three function, it can decompose specific equipment, after decomposition, you can get different levels and types of ore materials.
The synthesis function can synthesize low-grade magic stones, enhancement stones and fragments.

Refine: Equipment which is marked "Meltable" can be refined into ores of different levels and types. These ores are necessary material for crafting new equipment.
Equipment without soul cannot be refined.

Synthesize: Blenheim Magic Cube can synthesize different material into low-grade stones, gems, enhancement stones, all kinds of fragments and etc. Some advanced items may also be synthesized in the cube but it is not 100% successful. Once failed, you may get other items.

Decompose: Use Blenheim Magic Cube to decompose equipment into different kinds of material. The category and quantity of the product is uncertain, but in most cases, it will be wheat, pork or shred of leather cloth. Sometimes, you may get material for enhancement or element powder. You can use your soulless equipment for the decomposition.

Change Appearance of Equipment:

Repair Equipment:

Repair All Equipment: