I'm no expert on these things, but while the patent's SUMMARY suggests it protects the game as a whole and also separately protects the board and the Q3 piece, the CLAIMS section in the patent never lists the board or the piece as a separate claim--only several versions of the full game. (And the game description appears to cover, roughly, any chess variant played on a cross-shaped board and including the orthodox pieces plus the Q3--or maybe some different specific piece, since 'three spaces in any direction' certainly seems like it could be construed as covering more than 8 directions).
So if I understand this correctly, neither the name nor the movement pattern of the piece is protected. (Which makes sense, on account of all the prior art we've already cited.)
Though of course any original artwork you made to depict the piece is protected (no surprise there).