Iron Maw there is a big difference between this 2 thing though. One he think Akame can because her teigu and what he know about Esdes power unitl that point. Now in ch 26 he see her kill something like dotcor Stylish alone. And more about her power....of course he thought this especially as he is probably worried about Akame.I mean,he probally know that if Akame try to fight Esdes now she will Die before she even draw out Murasame.
And if we want be honest he not just see a bit of her power. He totally see a great deal of her power and see that she still fine after use all that power. Also i reapeat that she defeat alone something that the NR have to fight as team.
About ch 27 ,from what I know he change his Idea to try to bring Esdes to their side
.So he not say that for nothing.
Reaper@ I not think she need Tatsumi for that. She already know that what she does it's wrong. But her philosophy it's just like that. I'm sure that like Tatsumi will be more clear to us as well after ch 27.