Aleks Leyesaid: I'm with Half Centaur; it makes sense thematically. Perhaps this is a teaser for a Dark Beast graphical over-haul?
Not out of the question, certainly. Though if Dark Beasts were getting a rework, I'd hope Jagex would stick to the appearance of its Slayer mask/helm this time or at least adjust the mask and helm to match their new appearance. *cough* abyssal demon graphical update *cough*