Near Miss: I arrived to the top of the climb to find my partner had incorrectly set up the belay device into what he thought was 'direct to the anchor'. He said he wanted 'to practice'. Although he had intended to set up his tube style device in guide-mode it was not designed for this, so had in fact simply set up a floating plate which would have made a fall very difficult if not impossible to hold, requiring the brake hand go above the belay (out and away from his position - very strenuous).