I'm not sure this was the last we saw of Sudou. Usually characters can be believed to be dead once you see them dead or lethally wounded. Both is not the case for Sudou and Aaron, only for Aaron who was shot in the forehead.
As CKB wrote above he has been holding the gun and has been shooting at people several times. In this situation it will have been accumulated experience and adrenaline helping and it would be rather sad if he never got any better :D
To be honest I was really happy wit the way Akihito was handled in this chapter. He only draws the attention of the troops cornering Asami and does not take them out himself. That would have been a stupid Mary-Sue moment.
I read somewhere someone commenting that he would be a perfect Assassin. LOL! No. Not yet, not by far. And it is perfect this way.
He is still himself, he just learns, he grows, he gets more convicted. And I personally would find it much more compelling if even though he dared to shoot at Sudou without hesitation there would still be the flaw that he is not a perfect shot in a panic situation, and that he therefore didn't manage to kill.
Hi, can we just talk about the fact that Akihito finally shot someone? For a kid who was shown throughout the series to be unable to kill and unable to properly hold a gun, I have to say, I was pleasantly suprised when he shot with no hesitation this time around.