User blog comment:Jopjopjop/Volume 19 Spoilers/@comment-23847729-20141105105810/@comment-1359322-20141110233645

Even if Issei reaches High-class, situations like Volume 14 would still occur, Vampires looks down on other species from the start. Also do you think the Vampires would respect Issei a reincarnated Devil when they don't even respect the Vampires they transformed from humans or the hybrid children they gave birth to. No they won't, for starters the only reason why Elmen was trying to act humble towards Rias is because she's trying to ask a favor from her to lend her Gasper, if it weren't for that, i doubt she would be so polite to Rias.

And no, Issei isn't really the one opening the possibilities, he can't even use the Wyvern when Ddraig isn't around, that means the new power-up Issei obtain in Volume 16 can only be activated with Ddraig around, so it's not Issei's evolution it's Ddraig's.

And Sairaorg's injury is neglable, if Sairaorg was able to use both hands properly from the start, Issei wouldn't have lasted till the end. Hell if Sairaorg's right hand was at a perfect state back then, Sairaorg in his BB state would have decisively defeat Issei.

What's wrong with the weakest host thing, even Ddraig the spirit in the BG said that Issei's crap. Remember Issei is just the weakest host, no one said he's the weakest user, Ddraig even said Issei was the best Sekiyuutei ever. And the reason to that is because Issei is weak thus unlike the talented possessors of the past, who becomes arrogant, drowned in their own power and merely treat Ddraig as a tool thus is unable to truly master the BG, while Issei being weak, strives to become stronger and learns to depend on Ddraig thus Issei was able to master the BG, in a sense Issei already surpass the past possessors. Hell the weakest BG host thing was never even mentioned for a while already, i don't even understand why someone would keep bringing this up.

Regarding the Rias calling them children.

This is probably where you don't misunderstand since you don't understand Japanese but Rias said 子(ko) not 子供(kodomo), if Rias said kodomo, then yes it would be condescending but in this case, when Rias said what she said with the 子 word only, it was referring to young people rather than actual children. But since 子 is the Kanji for child/children, the translation has to write children, but the way it is interpreted is different. The Japanese language's interpretation of a word changes base on the situation and how one says it.