Aizawa cautions Yaoyorozu on underestimating Shirou just because he is more limited on what he can create, pointing out the he's much more skilled than her. Of course he would focus more on Shirou's skill than his Quirk strength; Aizawa's whole fighting style is built on the fact that without their Quirk, most villains in MHA aren't that strong. At that point, Shirou had demonstrated skill at not one but two different forms of martial arts; sword fighting and Japanese Archery.
This also explains why Aizawa is more antagonistic to Shirou than he is with the other students; while most of their strength is reliant on Quirks that he can erase, Shirou's isn't. Which means that Aizawa's main advantage is almost useless against him.
Why was Angra Mainyu killing blonde men and women? Remember two of the most well known blondes in the Nasuverse: Artoria and Gilgamesh. The former being responsible for destroying the Grail just as he was gonna finally be summoned, and the latter completely No Selling the effects of the Grail Mud thanks to his own ego and failing to summon him thanks to not taking Shirou seriously. He's pretty much using his victims as proxies for the two Servants that screwed him over.
It may have actually had more to do with the fact that the man he possessed was likely killed by Himiko Toga, as it was stated she went around killing any guy she liked before joining the League of Villians.
Confirmed to be Himiko Toga on the latest chapter.
It seems strange how easily Nezu gave Shirou permission for training sessions and how Nezu seemed quite happy about them, given that there would be a training camp in the summer, making the training sessions seem redundant. However, the training camp also serves as bait for the League of Villains. Of course Nezu would happily accept it, as these training sessions would prepare his students for the League of Villains' upcoming attack on the training camp.
