So i played the demo and liked it. I don't why, but for some reason I fear the spells and attacks you get in the demo are pretty much the only ones in the full game.
 
Am I right? Does the mage character get more? And does DeathSpank? Like a whirlwind or charge ability?

Don't know about the mage, but basically you get 4 spaces for weapons so what you're attacks do depend on what effects your weapon has (like fire damage for instance). Or you can equip justice weapons which are basically like special abilities you can use when your justice meter is full. You also get glyphs (I think that's what they're called) which let you perform special attacks. For instance the first one I got does a special attack if I attack with a cleaver and a fire weapon at the same time.