Shin no Nakama ja Nai to Yuusha no Party o Oidasareta node, Henkyou de Slow Life Suru Koto ni Shimashita

Blessings are actually double edged swords that can be Curses instead.

Ruti has the Hero blessing, which FORCES her to fight for others over her own choices for self preservation. It even turns her into human automaton by numbing her emotions, negating her ability to sleep or need of food.

So it's no wonder that she drinks the Demon elixir that is claimed to erase and replace Blessings. While it doesn't "do what it says on the label", she gains a secondary Blessing called New Truth that can control other Blessings; allowing Ruti to negate the downsides of Hero and keep the benefits.