I really don't have an answer as to why he was able to stop one out of three coffins, except to say that maybe he wasn't able to react quickly enough. That part kind of didnt make sense to me...but i could see if his reflexes weren't high enough to stop the other two. Oh yea...i just remembered that too... There shouldn't be anyway that Oro should be able to summon the 4th, since he was the one who created and used Shiki Fujin...weird.