Ahoy!
Burning blade is fun when contested and gets very stale and boring when not.
But the biggest problem with it is that you need to scuttle your ship to take it over. Once that is done and you sail around completing the rituals, you are forced to stay on it until you decide to finish your session. As I really doubt many pirates would spend several hours doing those rituals, then return the ship, only to catch a mermaid to your ''sunken ship'' with no supplies or emissary flag.
I would propse to introduce a new mechanic, giving a nod to the PoTC. What if when you take control of the burning blade, your ship gets 'trapped' in a bottle.
If you succesfully return it back to Flameheart, the ship respawns at the Reapers Hideout in same place you parked Burning blade. If you get sunk, your ship gets destroyed in the process.
Current mechanics give massive incentives for players to quit after the world event, no other world event does that, so I think some changes are in order.
