Well, it has admitted to be somewhat ambiguous. If you highlight "the demon resurrected from ancient times", then it would suggest that the demon itself has been resurrected. The problem though is that we have no supporting evidence to suggest a demon was involved in FSA's story.

On the other hand, "the evil device of the demon" could also be read as "the demon's evil device", in which case it would mean the Trident has been resurrected by Ganondorf. Since we know the Trident has been sealed in the Pyramid since ancient times, that interpretation is much more befitting of the story.

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What if Majora's Mask was never made? / The last interesting timeline topic on ZU /
Disproving the Divine Prank myth