The wizards' powers are overshadowed by pretty much every other sort of magic user
I'm not sure where you're getting this. Antorell in particular is pretty incompetent, but this is the case even relative to other wizards; he just happens to recur a lot. The wizards are able to assassinate a king (with help), kidnap a subsequent king, and then ultimately create a large long-term problem for a third king and his family. They're effective at causing trouble, they just don't win in the end. In a kids'-book sort of way, they fail in straightforward and sometimes almost cartoony ways without trying things an evil villain in an adult's book would with their powers, but this doesn't mean that they aren't powerful, it means that they aren't being discussed in a context where they can press the advantage.
they can be melted with soapy lemon water, or by pointing at them and saying the right word.
The word didn't work to start out. That was the more portable alternative to the buckets of water that had to be developed deliberately by Telemain; wizards aren't just inherently vulnerable to the word "argelfraster".
arming the protagonists with lightsabers
I don't think the protagonists are overpowered except maybe Mendanbar (and his book has his magic sword on the fritz for most of the action anyway). By and large they solve their problems by thinking about their resources, going to the correct places, and confronting the bad guys, not by just having ultra-powerful weapons. (Heck, Cimorene got a wish from a genie in book one and used it to get a spell ingredient instead of, like, omnipotence.)
I'm not sure where you're getting this. Antorell in particular is pretty incompetent, but this is the case even relative to other wizards; he just happens to recur a lot. The wizards are able to assassinate a king (with help), kidnap a subsequent king, and then ultimately create a large long-term problem for a third king and his family. They're effective at causing trouble, they just don't win in the end.
They are effective at causing trouble, but they manage to do so despite being pretty heavily disadvantaged magic-wise compared to the protagonists. Zem...
Follow-up To: On the Care and Feeding of Young Rationalists
Related on OB: Formative Youth
Eliezer suspects he may have chosen an altruistic life because of Thundercats.
Nominull thinks his path to truth-seeking might have been lit by Asimov's Robot stories.
PhilGoetz suggests that Ender's Game has warped the psyches of many intelligent people.
For good or ill, we seem to agree that fiction strongly influences the way we grow up, and the people we come to be.
So for those of us with the tremendous task of bringing new sentience into the world, it seems sensible to spend some time thinking about what fictions our charges will be exposed to.
The natural counter-part to this question is, of course, are there any particular fictions, or types of fiction, to which we should avoid exposing our children?
Again, this is a pattern we see more commonly in the religious community -- and the rest of us tend to look on and laugh at the prudery on display. Still, the general idea doesn't seem to be something we can reject out of hand. So far as we can tell, all (currently existing) minds are vulnerable to being hacked, young minds more than others. If we determine that a particular piece of fiction, or a particular kind of fiction, tends to reliably and destructively hack vulnerable minds, that seems a disproportionate consequence for pulling the wrong book off the shelf.
So, what books, what films, what stories would you say affected your childhood for the better? What stories do you wish you had encountered earlier? If there are any members of the Bardic Conspiracy present, what sorts of stories should we start telling? Finally, what stories (if any) should young minds not encounter until they have developed some additional robustness?
ETA: If there are particular stories which you think the (adult) members of the community would benefit from, please feel free to share these as well.
ETA2: My wildly optimistic best-case scenario for this post would be someone actually writing a rationalist children's story in the comments thread.
ETA3: On second thought, this edit has become its own post.