You'll probably boost your intelligence a lot as a mage, so look for weapons that do more magic than normal damage, usually maces and warhammers. There are several 'sets' in the game as well, that boost your magical properties significantly when worn together.
Also, investing skillpoints in magic spells is definitely not a waste! Wizards with 10 or even 15 points in spells like Magic Missile and Fireball are VERY powerful.
Still, if you really don't like the skills you've been assigning points in, you can unlearn them all and redistribute your points. You'll need to talk to your skill trainer in your Battle Tower to do this, but perhaps you're not quite that far into the game yet. Also, this costs quite a bit of gold, so don't do this too often!
