All of this seems to point in the favor of the blockade breaker option, because it's hard to shiv an ironclad, but there is one potential avenue I'm concerned about there, and that is to bait the Grudgy Dwarves. If some Marienburgers could fake to the Dwarves that the Elves were interfering with the counter-embargo, and a particularly ornery Dwarf captain could be persuaded to do something impolitic to the Elven quarter, that would be, uh, poor. Alternately, if the Marienburgers just chose some sacrificial ponds to throw at the Dwarves until one of them attacked something that wasn't a Naval asset and called upon Ulthuan's treaty, that would lead to issues. Now, Dwarves are a resilient lot, and I don't think that such a a ploy would be likely to work. Why, I think it would be an outright longshot.