Kirito attempts to reach Eugeo’s suppressed memories while their swords clash. Although Eugeo is under the control of a "piety module," his bond with Kirito causes him to hesitate as original memories begin to resurface.
For more detailed discussion and community reactions, you can visit the Alicization Episode 21 Discussion Thread on Fandom. Sword Art Online Alicization Episode 21
In a strategic move, Eugeo uses his Blue Rose Sword to freeze both Kirito and Alice in ice.