Could Mael use The One like Escanor?
As far as we know, Mael does not possess "The One", but does not have a weaker form at night either. It must be noted that Ludociel refers to this Grace as Sun (「太たい陽よう Taiyō」), and not Sunshine, which may imply there is a difference between Escanor and Mael's use of this power.

A popular fan theory is that Escanor possesses an unnamed innate magical power which grants him power and strength based on the time of day ; and that this innate power interacts with the Sun Grace to create Sunshine. But this is only a theory.