I think I'd like to see the chins alittle less square and more rounded, and the right arms (well, on our left) stretch out from the bodies abit to far (Also the 1 pixel width part of the dagger I think will look abit odd like the blade is 'hovering' when made to a smaller scale). Other than that they are quite good and simple for the style.
I think the main thing to keep in mind with class trees is to try and make each path a viable option, in similar games players get frustrated if they spend 50 levels working towards Paladin only to find out Paladin is inferior to Spellsword. The obvious conundrum is you also want to make each path different enough to each other to have players want to try new combinations each game.

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