Thanks, tallman.
These are good points, but not bugs.
Spellcasters cannot be hurt by their own magic. We could have gone either way on that, but we decided against letting spellcaster blow themselves up. :)
When the human guards, he uses the bonus of his sword or shield, whichever is higher. He's getting +12 from his +11 sword bonus, along with the standard +1 for guarding.
--Alex