User blog comment:B214/Volume 21 info & spoilers/@comment-3290441-20160626173222/@comment-93.105.241.146-20160626232623

Actually I doubt he did it on his own. I rather think he made sacrafices of his own like some of his top tier angels. Plus it was stated that he feared Ophis who is on par with 666. So while sealing it is impressive it's clear he is not as strong as it is.