WordNet sense 1 (very irritable):

bristly, splenetic, waspish

WordNet sense 2 (having an irritable and unpleasant disposition):

ill-natured

WordNet sense 3 (having or covered with protective barbs or quills or spines or thorns or setae etc.):

barbed, barbellate, spiny, thorny, setaceous, briary, briery, bristled, burred, burry, setose

WordNet sense 4 ((used of plants and animals) furnished with bristles and thorns):

armed