Pawn: Something given as security for the payment of borrowed money; a pledge.
This first definition has nothing to do with the Latin word for foot. Instead, it comes from an Old French word meaning pledge, or security.
The pawn on the chess board, however, does from from the Latin word for foot.
The Old French word peon, the source of our English pawn, comes from the Latin word pedo, someone who goes on foot. In Medieval Latin, a pedonem was a foot soldier. Pedo, of course comes from the Latin word for foot, pes, pedis.