Each resource in the game used for fittings has primary stats that are directly associated to that resource in some fashion such as Physical Resistance, Accuracy, and so on. These resource attributes are not randomly assigned. Each material has multiple attributes that are assigned into three categories: Primary, Secondary, and Tertiary.
Primary attributes have the highest values (typically 7-10) with secondary in the middle (4-6) and tertiary at the bottom (1-3). These values are static so a chunk of calibrite will always have the same attributes, but it can have a random grade value associated with it that impacts the rarity and significant worth of the material (grade A being the best).
The next step in the process is refining the material. Calibrite ore's primary attribute is Physical Resistance; there is no other ore that can provide as high a bonus to Physical Resistance as Calibrite. As part of the crafting process, refinement requires the player to take the harvested ore and create a refined metal bar. Based on the agents players use in the recipe, they get to choose which attributes are on the final product. With more than ten attributes available on each ore, players must decide which ones are most important to them as they create the refined metal. The refinement system does not only use pure ores, but allows for combinations of ores and minerals to create alloys which have unique attributes of their own. The refined results are then used by another craftsman (or if you are skilled enough) in another recipe to create a fitting with the refined materials.
As mentioned with fittings there is a letter classification for fittings such as "A", "C", or "E". These are typically comprised of primary, secondary, and tertiary stats much like the materials such as calibrite.
"A" class fittings primarily consist of the core combat attributes dealing with damage increase and mitigation across the different damage types (physical, energy, fire, etc) and have secondary and tertiary stats that are more limited in value.
"C" class fittings deal with recovery/retention style stats for health, energy, momentum, and endurance and might include some secondary and tertiary stats available in "A" class fittings.
Across the spectrum, players can add multiple stats and make detailed choices about customization, but the system is tailored to prevent people from stacking full damage on everything and creating an excessively unbalanced weapon or piece of armor because each fitting has a limit of each attribute that can be placed on it from the refined metal used to create it. The crafted fitting takes the attributes passed to it by the refined metal and its grade to spit out the stats. When the fitting is slotted in a weapon or piece of armor equipped to a character, those stats are added to the character or used by the weapon or armor when used.