Heh... to level up magic for a Barbarian, you need to have a castle that offers that magic... and if you have a castle, it's better to use a Mage with that magic, as they have more mana and skills (although Light Mages can reduce Battle Discipline)... (in principle, it's already low for me... and it's different for everyone :\... I don't know why... they're all the same race, I leveled up the Tactics skill for the leader, and it's 5, but the mobs have less...)
P.S. Relying on books... khm... isn't a very good option either), so it's better to focus on Battle and Tactics... or maybe even another hero)
p.s. you might get lucky and get a dispel spell right away from the basic magic, for example, from the Order magic.