What changed with Gilgamesh?
I'm surprised more people don't know this.
See the joke is that Greg thought he had the "strongest lance" in the world, Bradamante, Nael van Darnus' signature weapon. One of Nael's moves, as a servant of Bahamut, is Megaflare. However Gilgamesh apparently got tricked and the lance he has while looking alike is actually
Pradamante. He attempts to cast Megaflare fighting you, but it doesn't work, which is why he's shocked the lance he has isn't actually the real deal. English dialogue completely removed him calling out Megaflare.
This is a reference to Gilgamesh (in FF as a whole) having a habit of using Excalipoor, a replica of Excalibur which always does 1 damage.