Always carry a antifire shield, just in case, as well as a bit of food.
Attacking these is stupidly slow, due to the halberd. Also, a Dragon Halberd would be much better, but I haven't finished Regicide yet...
As for loot, black dragonhides with each kill, and of course a chance of truly amazing drops such as a Visage. Bury the bones on the spot.
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black dragons blacks dragon