Knight, e.g (5)
(Other definitions for piece that I've seen before include "Firearm -- collector's item" , "Unpleasant character" , "Queen on board, perhaps" , "Musical work; bit" , "Portion, coin, item" .)
(Other definitions for sir that I've seen before include "Formal term of address" , "Feted fellow" , "Honorary male title" , "Polite term of address for a man" , "Formal and deferential address to a man" .)