Beguiler isn't really the best class to be picking up melee abilities with. If you want to improve your character's effectiveness in combat, consider getting Shadow Conjuration and/or Shadow Evocation, and take max ranks in UMD and pick up a few wands of super-effective low-level spells. A single level of Mindbender would be a good choice, but other than that I wouldn't multiclass out of it.

I'm currently playing a Beguiler 10, we've only seen one combat since I joined the group four weeks ago, and this character has turned out to be the MVP every session. I'd have to say that Beguiler is the single best class for any noncombat situation you could think of, and it has plenty of options for combat as well. You just have to think as a battlefield controller rather than a damage dealer.