In reality, Morne didn't move his arms at all. The second the voices resumed their carnage, his Sense expanded and his feet started moving of their own accord. The battle to follow was entirely within his own mind.
And what a difficult battle it was. Morne had grossly underestimated just how powerful each voice was, or perhaps he just didn't care.
He lashed out with mental knives forged of hatred and fury, sinking them into a screaming voice and holding it down with all of his might as the luster of a star outside slowly faded.
But while he was handling one, there were hundreds more that surged past him, and thousands more after that, each one eager to be the new Morne.
Morne's retaliation appeared to have set them off, and they turned on each other once they entered his mindscape, smothering and stabbing one another. If it were not for this hostility, Morne wouldn't have stood a chance.