"Ironically Joselin, the head of the julijamu is not at question - albiet gruesome - as it is the heads of the skinwalkers you took. At a casual glance, they are the heads of men with a fiendish lion or tiger upon their brow. In and of themselves, generally, a head is not considered unholy - 'tis what you do with them and why you take them that matters most.
"Until such time as you actually consecrate thy ship, or install an altar and render the vessel hallowed ground, the presence of such grim trophies have no innately deleterious effects. Although the morale of one's crew could be another matter to settle."