Blistering Pete is the owner of Blistering Pete's weapons shop in Windemere. A former pirate forced to lay low for a while after a run-in with the Royal Navy, he presumably has a treasure buried somewhere, waiting for him. It's possible this might refer to the huge treasure found east of Windemere on the Secret Duck Isle, although the treasure isn't buried.
Blistering Pete sells bombs, longwords and claw swords.