Nora attacked him several times with Ayakashi, seeming with intent to kill. However, we find out later that if Nora really wants to kill Yukine, she just needs to rekindle his curiosity about his former life. That makes all her attacks seem kind of pointless.
In reality, Nora wanted to infuse fear in Yukine's mind, as she was trying to remove all Yato's connections which connect Yato to goodwill.
Basically, she wanted to break Yato's connection with Yukine, him being Yato's (Yaboku's) exemplar. She was continuously trying to make Yukine leave Yato (in fear), so that she can awoke the previous Yato, whose intention was to kill.
As that would have left Yato in enraged and mentally weak state (easy to control) that the death of Yukine (which could have resulted in fall of Yato).
Nora wanted to bring out Yato's dark side. She despised the fact that Yato found someone better than her. Not to forget there was Rabo-sama who was secretly controlling Yato