The YouTuber brought up Fierce Deity comes from the Fierce or Wrathful Deities of Buddhism who fight vices and great evil. So I do wonder if it was intended to be evil or dark at all?
The Fierce Deity Mask maybe evil and dark, but Link’s purity of heart and the Triforce of Courage kept him in control of it.
A YouTuber showed that the marks on Fierce Deity face match The Hylian Shield:
On his chest plate is a single triangle, one of the pieces of The Triforce, Courage...