One lesson Desmond had to learn the hard way was that no matter how loud one roared, what really mattered was the muscle one had to back one's ferocity. In the particular case of Emerard, or the beast that Emerard had become, well, Desmond had no intention of competing with that thing.
Using the boost he got from burning the drop of essential blood he drained from Mathias Lupan, Desmond continued to scamper around the huge necrotic beast. Unlike the rest of the Darkblood, whose powers were quite diverse, Desmond had only one ability bestowed by his lineage on top of an above-average physique.