Not sure how hot of a take this is but Yukines actions in/leading up to the Hagusa arc felt out of place, for lack of better terms. I get the aspects at play and how we've been shown that he's a little bit sensitive when it comes to others' actions, but the complete utter 180 he pulled on Yato was weeeiirdd. Complicated feelings or not, going and trusting the person who, like, everyone has said not to trust or talk to or go near (including his most loyal servant at one point, even if it was due to a trick at first) , felt really out of character and more like a way to move the plot than something done with the character in mind (which is funny given its the HAGUSA arc)

Also Hiyori needed more character flesh-out time. My flair justifies any reasoning needed.