Shion/Chronology

Empowerment
She first joined Rimuru following the Ogre Village's destruction and was named along with the others after Benimaru accepted Rimuru's offer of servitude in Rimuru's kingdom of Tempest.

Demon Lord Awakening
Due to the one hundred invading Falmuth vanguard knights accompanied by their three Otherworlders and the Prison Field barrier placed around Rimuru City, Shion was weakened significantly and ended up dying protecting a child during the invasion. However, she was later revived by Raphael and her Harvest Festival gift enabled her to evolve into a Wicked Oni. During the Harvest Festival, she wished for her cooking to be delicious, thus obtaining the Unique Skill Cook.

During the Walpurgis Banquet, Shion fought against Clayman and completely overpowered all his attacks.

Saint-Monster Confrontation
When the Holy Knights were marching to Tempest to kill Demon Lord Rimuru because of a misunderstanding. Shion pushed back against several members of the Ten Great Saints on her own, completely deflecting all their attacks and breaking through a Holy Purification Barrier with her odachi Hercules' Edge.

Shion defeated all three of Demon Lord Dagruel's sons when they came to Tempest to challenge Rimuru without even unsheathing her odachi. Later, they became her students.