to weaken, to wane, to falter
Mais on sentit bientôt que ce journal lui-même commençait à faiblir.
But soon it became clear that the newspaper itself was beginning to falter.
Au bout d'un moment, son enthousiasme a commencé à faiblir.
After a while, his enthusiasm began to wane.
Mais les autres continueront d'avancer sans faiblir.
But the others will keep moving forward without faltering.
— Dune : Deuxième partie (2024)