'Calm down.'
Zero point two seconds after Sai hit the ground, Katarina immediately activated a magic she gained recently, calm mind.
Her rampaging emotions were forcefully subdued and she entered a state of unparalleled calmness and she assessed the situation.
Calm mind was a magic that allowed one to maintain an inhumane amount of calmness for a single price; as soon as the magic is turned off, the user experiences a sudden flood if emotions and depending on what they might have felt during the time the magic was active, they could even commit suicide.
Which was why Katarina set a condition for its activation. Only when an emotional trauma so great it would affect her severely would it activate.
'Looks like he was quite a significant existence in my heart.' She calmly observed and turned her gaze to the Reaper who gazed at the fallen figure of Sai.