Arrow Key Up: Slash Downwards.
Arrow Key Right: Slash Left to Right.
Arrow Key Down: Thrust.
Space Key: Block - when using sword.
Space Key 2x: Parry.
Space Key: Ready Arrow/Bolt - when using bow or crossbow.
Mouse: Use your mouse to aim. Click to pick target.
Space Key: Fire - use for bow or crossbow and only after picking target.
If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).