It's really hard to find, it's a clickable object under the bridge in the water. Also this is probably the coolest bridge in the game.
Turn in "Missing Orders" in the inn, accept "Swamp Talker"
Jarquia, a purple-skinned murloc wanders the beach, is who you need to kill to get the goodsteel's balanced flameberge.
Get the follow up, turn in the follow up. Hearth to Booty Bay. Get on the boat to Ratchet, go to Dustwallow marsh and start circuit 5