These upgrades improve the players stats depending on which upgrade element was used and, although minor, can provide an extra elemental kick to boost damage output or increase survivability with increased health.
All upgrades are also visually represented on the weapon in the form a single voxel per block, allowing you to make your weapon look the way you want, with a limit of 32 blocks however.
Please note that while you can always relocate pre-existing upgrade cubes, you are currently unable to remove a cube from your weapon without permanently deleting it. Once a block is placed, you must delete it in order to remove it from your weapon.
Because of this limitation, it is advised that you spend your upgrades with care. By selecting any pre-existing cubes and moving it outside the customization box before clicking, you will delete the block. This action is irreversible.
In order to rotate the weapon you need to click and hold the middle mouse button while moving the mouse cursor in the desired direction you wish to rotate your weapon.
An addition or alternative to weapon customization is adaption. Adaptation works on any item that can be worn by a player and will convert it to your current power level, which means you may either upgrade items with a low power level or downgrade items with too high power level so that you may use it.
Because of the rarity of platinum coins early in the game, you might want to spend them carefully.
There appears to be a level (power) restriction on spirit infusing weapons. Currently the power limit difference appears to be minimum -10 of n, where n is the weapon level. Likewise the maximum is the same level as the weapon level.
Example: A weapon with power level +41 can only be infused with Spirit cubes that are of power level 31 to 41.
To customize your weapons, you'll need to locate the blacksmith in a city's crafting district.
You can use different cubes to customize your weapons: wood, iron, silver or gold to add additional damage to a weapon. These can be obtained by destroying deposits found in caves. You can smelt the nuggets in a furnace located at the blacksmith.
Wood logs are found in bushes, they can be sawed into wood cubes.
Spirit cubes are obtained by killing quest bosses or rare enemies, when added to a weapon, it will slightly glow while fighting, and add a special effect: fire spirit adds damage, ice spirit slow the enemy's movement and attack speed unholy spirit will absorb health from an enemy and wind spirit will increase your own movement and attack speed.
At the blacksmith, you'll find the customization table, use this to place a weapon in, and add cubes. Note that you can only add cubes which are the same material (wood, iron, silver and gold) or have a power level higher or equal to the spirit cube's level. You can turn your weapon by holding your middle mouse button.