User blog comment:SpookyBoogie27/Light Novel Spoilers/@comment-8.28.150.75-20140210091944/@comment-1359322-20140211001006

ಠ_ಠ. That isn't embarrassing for Issei at all. If anything, it's meant to be a great feat for Saji. ಠ_ಠ

Saji attached his Absorption Line towards Issei which will drained Issei's blood that he trained to the level that it won't detach unless the Rating Game is over. Also

"However, how did Saji create such an attack? I had heard that he had low magic like me. Yet, how was he able to release such power?

At that moment, I opened my eyes widely. Because Saji’s Sacred Gear had its line connected to his chest— to his heart.

—The source of Saji’s continuous attacks was his life-force!?

“Saji! You! Are you converting your own life-force…into magic power!?”"