RUNDOWN:
Clothes: obvious
Magic: Sells Magic spells, Magic enchanted clothing, and magic weapons. Also sells potions (Made with Magic, not Alchemy [Which means the effect they have on Soren and other alchemists is not as strong or in some cases non existant])
Skills : Sells Generic Skills, Stylizers, and Skill Allocation and Management Systems. "SAMS" as they are called, are used to level up skills and learn skills from your skills. Some skills cannot be learned without a SAMS unit, while older skills do not need SAMS. SAMS lets you level up skills according to what you want them to be.