To increase the stats of equipment, it needs to be quenched. Open the “Workshop - Quench” tab. You can transfer random parameters from equipment of the same type to your current gear. Only equipment with random stats can be quenched. Level of gear used as quenching material can’t exceed the current equipment’s level.
The level of equipment items determines max amount of random stats they can hold. Higher level gear can have up to 4 random stat slots.
If there are no empty random stat slots on the piece of equipment, quenching it will replace one of the random stats with a new one. The replaced stat will be lost.
Equipment can only hold one random stat of the same type. Attempting to add another stat with similar bonus will replace the stat in the upgraded equipment if the new value is higher. Alternatively it will result in an error message and the quenching process will fail.