[Ranylyn]

Rule 1 to combat with melee weapons: Keep your weapon between yourself and your opponent. It is more than an offensive tool. It is your defense. If they get their weapon past yours, it hurts. A lot. And naturally, this only works if you can see your opponent. As in, if they're not behind you.

There's literally no reason to be able to parry attacks from further behind you than 1 square. It's BEHIND YOU. Assuming you DID have some kind of magical 360 degree vision like... I dunno... armor of eyes? Even if you could see it coming, your parrying implements (Weapon and shield) remain in front of you, rendering you unable to react in time.

This is why Watchful Eye is a thing: To simulate following your opponent's movements and keeping your weapon and shield facing them. As such, if they are behind the BK (and thus having either bypassed watchful eye or having it not been used agains them) they should not be magically parry-able if they're 2+ spaces back.