Uuuh, how did he attack the guild master (without actually attacking or even approaching guild master)? And why did the barrier suddenly break after he failed (despite not attacking after it got blocked? And why did the head pop off after barrier broke (despite not attacking - or approaching, still - after barrier broke)?
Of is it canon that he literally attacked through the fourth walls, by merely pointing/laying his sword across the manga's panels? As opposed to attacking through the regular dimensions of space and time? Because that is the only way I can explain things, and the sword does exceed its own panel on that page (though it never hit his neck).