“shouted.” The Hebrew word can mean just shout or cry out, but it often refers to a war cry, and that is its likely meaning here. Samson had killed many Philistines and they were hungry for revenge.
“the spirit of Yahweh rushed upon him.” The spirit from Yahweh powerfully worked in him, and Samson would have recognized it.
“flax that has been burned with fire.” Lamp wicks were often made with flax, and when it has been burned it is very fragile; a good comparison would be our candle wicks after they have been burned, they are very fragile and take no effort to break. Samson would have recognized that this was the work of Yahweh and that he was being helped by Yahweh.