User blog comment:Jopjopjop/Volume 19 Spoilers/@comment-1.53.124.174-20150712141105/@comment-42.112.87.13-20150713043545

@B214

“—Uh! Cristaldi-sensei!”

The man that Irina addressed was holding a sword which was capable of emitting a holy aura. It was that sword which was currently blocking Irina’s Hauteclere. Cristaldi—. That was definitely what Irina called him. It looks like this middle-aged man was the third person behind the rebellion — Ewald Cristaldi! He was the famous previous wielder of Excalibur! Ewald Cristaldi used the weapon in his hands to push Irina back, then he said

“…Warrior Irina, you shouldn’t limit your vision so narrowly.”

…This man’s body also didn’t appear to have any openings. —But, there was one person, who rushed towards him with a sword!

“The previous wielder of Excalibur…!”

It was Kiba! He was wielding a holy-demonic sword, pointing it at Ewald Cristaldi!

“Come on! Let’s decide this!” Right from vol 19 Life 1, so there you go. We don't know how Xenovia defeated Strada due to the lack of details, and yes even when in the spoiler she used a knee attack there could be something more than that in the battle. I will wait for that but the fact that Cristaldi being the enemy, he appeared, talked or fought a bit then retreated without major damage is something you cannot change, that is the repetitive format of DxD in 3 vol straight.