On 16 December 2017, Berthier became the first Singaporean fencer to win a Junior World Cup title at the Havana leg in Cuba in the eight-leg series.

She was then chosen alongside wushu athlete Jowen Lim as the flagbearers for the 2022 Asian Games held at Hangzhou, China in 2023.

Ranked 28th in the world in the women’s foil, she claimed points at the International Fencing Federation (FIE) Grand Prix in Washington DC by finishing joint-20th.

[10] She parted ways with her previous coach Amgad Khazbak also worked with Kiefer and was unable to be with Berthier during tournaments and the Olympics Games due to conflict of interest.

[10] Berthier will be training with the Singapore national team's foil head coach, Oleg Matseichuk, for 3 months as part of her preparations for the Paris Olympics.