It is implied that the Darksaber became heavy and unwieldy for the former Sith Lord after his defeat at the hands of Darth Sidious. Whether it was because the Darksaber had judged Maul to be unworthy after his loss to Sidious or whether it had concluded that Maul was no longer serving the best interests of Madalore will have to be decided by the historians. (Technically, Maul did use Darksaber after his defeat in his battle with General Grievous, but that was in Dark Horse Comics and simply, for canon purposes, IMHO, isn’t on par with the Star Wars films and TV series projects.)