Weaving

"The essence of steel is a pitiful thing. An alloy created by man; it is man’s creature, wholly subservient to him. Smelted and malleable, its very nature is to be manipulated by the will of others. Steel has no spirit to resist. These bars were no less accommodating of even Solis’ inept weaving, and soon they wilted at his touch."

"Weaving" is how humans manipulate magic. It is primarily done by forcing an object to obey the will of the Weaver. Because of this, man-made objects (who's physicality has already been changed by man's will) are easiest to manipulate by weaving. Things that were once alive and now dead are the hardest to weave.

Things that are alive cannot be affected by human magic.