LogFAQs > #985093165

Well even killing her should have gotten you her badge to buy her weapon. That actually does have Arcane damage and scaling. It's very good too if you're okay with R1 spamming.

Regardless it'd be a good idea to progress further, since it's easier to find upgrade materials in the late game. But honestly you could just stick with the Saw Spear if you don't feel the need to experiment with anything else, it can easily carry you all the way to the end.