User blog comment:B214/Volume 23 discussion blog/@comment-87.9.174.130-20170325204325/@comment-87.9.174.130-20170325225940

Probably the Sephiroth Graal, before it was turned into 3 different Graals by Valerie with her Sub-Species, in some battle was broken (and then repaired or regenerated alone, like the armor of Issei and Vali balance breakers for example), and that piece was retrieved by someone and still had some power in it. Remember when Issei took Vali's power by one of his gems? Maybe something like that.