When I see the base alch - it makes me think of alchemist as old time name for a chemist, back then as a practice that those who understand the stoichiometry of chemicals (and materials, objects) and can induce them to create desired compounds. Usually the alchemist in my mind is a guy with white hair, horn rimmed or dark glasses and wearing a lab coat.
And yeah, alchemy is the mastery skill of that.
Didn't look it up, straight from my mind.
Sort of like Leonardo da Vinci, eh? He dabbled in alchemy as well.