I learned the hard way and started as Cleric and Shadowblade.
That's just not true. I'm playing with exact this setup and my shadowblade has the ability to crowd-control (stun, blind), buff (desecration), kill (i can backstab an orc to death in one turn). And he also runs fast (fast track + talent). Oh and he summons armored skeletons. I have no AP penalties, I do have change penalties due to low attributes but they are only up to -10% which is negligible.
My cleric is a buffer/debuffer +offheal. She also cripples targets for Madora to kill (with bully talent) The only thing she lacks is AP but I'm working on it
So the hybrids are fine. Of course a pure mage can master 3 or all the elemental schools with ease, but still shadowblade is more then viable
And btw Loremaster is also a useful skill: try hovering your enemy with Ctrl pressed: the amount of information you get depends on Loremaster
