He hadn't anticipated that his last sword strike would fail to decapitate Simon. Not even the second slash did more than wound Simon. The displayed strength indicated that Simon was no newcomer to the Fighter's Realm but rather at the level of a Veteran Fighter. He wouldn't fall instantly at the hands of a top-tier Combatant!
Of course, part of the reason was Eye Demon himself. Without his well-matched Spiral Eyed Sword, his strength had fallen within the pinnacle Fighter's Realm.
Otherwise, with the sharpness of the Spiral Eyed Sword, Simon's Fist Guards would not have been able to block any of the three strikes he had just launched; his palm would have been severed.
"Interesting, but that's all it is... interesting..."
The Eye Demon once again tightened his grip on the Cross Sword in his hand, the Heart-eye Secret Technique locking onto Simon: "You may have blocked one strike, three strikes. But what about five? Ten? A hundred? Death is inevitable after all..."