Essence Weaving is the practice of grafting the properties of one naturally occurring resource into another. This can apply to elementary particles, but is generally in regard to compound objects.
For example, weaving the essence of ice into the blade of a sword. Some amount of ice would be consumed and the blade would become chilling to the touch.
As the Weaver grows in skill, they are able to handle more complex and powerful reagents. For instance, fusing the essence of an octopus into a set of clothes to create a morphing camoflage suit.
Whatever the ingredients, a third resouce must also be consumed as a fuel. Anything can be used as fuel, but some materials are more efficient and stable than others. Wood, for instance, is a good source for small projects, but requires large quantities for complex enchantments. Gold, however, is very costly, but the volume needed is miniscule in comparison.