YES, he does drop his own special gear.The hat and his staff are dropped.He also drops his glasses, and his sprocket key.Bishop doesn't drop this robe or shoes sadly.And deacon doesn't drop any boss gear.I've been farming bishop and so far I have four staffs, and three hats.
Bishop does drop his own unique gear, but Deacon currently does not.
Deacon is Book 10's End-of-Book boss, you know, so I surely think he should get his own unique drops, like his hat, his weapons, & his outfit. If I would obtain his outfit, I'd look amazing in them. Plus, Ratbeard says some of his items recorded in the P101Central Wiki aren't real items, if I recall.