What about a dragon that, instead of bile-based attack, we had one that could shoot quills, spines, or other sharp projectiles, and its secondary was also related to its defensive physical attributes?
Alternatively it would just be nice to see dragons able to have a third sort of attack where they just use their horns, spines, claws, etc. They've got all these offensive and defensive attributes in the models, and real animals would make use of them as such.