The FootKnight is a very simple boss. Its only attack is to rush towards the player and stab them, which doesn't deal too much damage. It has a lot of HP and defense, though, so it will take a while to whittle it down. Normal attacks won't do much, so use charged attacks or alchemy at a decent level.
The player doesn't get much experience or gold for the victory, fitting given the low difficulty of the fight.
Through a glitch to open the eastern staircase early, the player can leave the Chessboard without defeating the FootKnight, but it will remain if the player returns later in the game.