He is accomplishing absolutely nothing with his knife. Which isn't really that surprising; an arm pressed to his side means he can't stab very well, and it's not even really meant to be anything more than a last resort. The knife goes back into his boot, and he grabs a lyrium vial from his belt pouch, scooting back quickly and downing the whole thing. It tastes as awful as usual, but maybe he can help soon. In the meantime, he flings the empty vial at the obnoxious Butcher while Milady dances around the Hawk.