STR = Melee hit damage, at least for Auto Attack damage. If you really want to melee then you need to up your STR to hit harder.
INT = More spell damage.
Not sure what to tell you about fighting the Wizard (I don't play on a PvP server) though the buffs we get are almost exclusively cold / heat... I can take out Wizards with little effort because I resist / mitigate their big hit enough to come at them swinging while they are scratching their heads wondering why I didn't bite it from their nuke.