So i just final ascend her and her whim of the goddess skill to lv 10 but her stat seems pretty underwhelming. Do i need to grail her or she is find as it is?
She's not used for her stats, she's used for her bonuses against certain enemies.
She'll deal 2x damage against Sabers, and unimaginable damage against MALE Sabers.
She's not a great servant outside of specific fights. But she's a great one to have around for those fights.
Everyone has been warning since release that you'll need Euryale for certain Camelot fights (The chapter coming out tomorrow!). While claims are sometimes exaggerated, she makes that chapter much easier so it's recommended to upgrade her as much as you can before you get deep into the chapter.
