His protection being attached to an attack trigger is actually perfect, depicting how Cecil leads from the front in FF4's latter half, uniting his friends to stand against both his former kingdom and the cosmic threat of Zeromus
Panharmonicon is already an extremely powerful Commander card, and Virtue of Knowledge provides you with almost identical benefits
Giving all your dragons +3/+3 for just 4 mana is an absurd rate, especially when you have multiple creatures already on the board
That said, Hearthhull does already come with a sacrifice effect attached, as do many sacrifice-themed cards
That shuts down Treasure tokens, Clue tokens, Food, Blood tokens, and many more, not just as utility, but as combo pieces