How many people did Sarah kill? Not many.
As a cadet, she did missions and had to hunt down the Dungeon beasts quite often. But that's when she was pretty weak and all those monsters were killed by a light explosion by Sarah now.
Since Sarah was in closed doors training and only came out as a level 9 when Varian was fighting the Sovereign Undead, her kill count was very low.
As a result, Sarah was able to finish off her share of dead and move to Enigma and Sia's.
"Roar!"
"Kaaa!"
"Sia! Sia!"
Unlike her, Enigma had killed dozens of level 9s during the recent war. Even before that, when she fought alongside the Shadow Guardians, she assassinated some powerful level 9 Abyssals. Moreover, she also assassinated some level 9 human powerhouses.
The total number of level 9 she had to face easily crossed a hundred. And even if Enigma was stronger than ever, she was completely overwhelmed.