The word is suspicious in that it not attested elsewhere. Assuming it is genuine (and leaving aside the unlikely possibility that this is aberrant sense of pet¹), this chess term has to be interpreted either an unusual shortened form of peonet (as the editor of S Geo proposes) or as a word related to (and perhaps a diminutive of) pé¹ (‘foot’), in the sense that the pawn is considered a foot-soldier in the game of chess (see also peon andpeonet).