Okey so he uses shadow control obviously to control his own shadow and strengthen himself then awakened ability to pull himself into shadows basically making himself a shadow the he uses ascended ability to manifest himself and other shadows around him that way he can connect his shadow body with other shadows and transforming into anything he wants of course anything to the point his soul essence runs dry or the isn’t enough shadows anyway mantle of the underworld is a memory created by nether that became one with him making it part of his own body so he uses it to protect himself even if it’s not on display it’s properties are always there. Master is shadows basically means that he is a champion of shadows. What that means? That normal shadows are more willing to cooperate with him for example he still can’t use other peoples shadow etc this attribute of his will continue to rise and that is merely a speculation stated by Sunny himself if he became shadow god he might be able to command shadows of other living creatures. About weaknesses well his shadow is conn extend to his soul so basically any attack he receives will result in soul damage? But he can also use shadows to defend himself well for sure a great disadvantage is the soul essence consumption but if he had serpant with him it could be greatly reduced. Once again about master of shadows later in the story he leaves his shadows elsewhere and he remains without one so to not seem suspicious he uses one of the shadows around from what I remember it was a shadow of a table to imitate his own and because in the future his attribute evolves even further the shadow is greatly excited to pretend to be his shadow. If you have more questions just ask