Magic is a ghost story, magic is a tickling feeling in the back of your mind that isn't necessarily yours. It's a gull looking at you with jet black eyes, a lantern that rocks against the breeze. Some are more attuned to this than others, but it can be as much a blessing as it can be a curse.
Politics in this world are of utmost importance. The many small islands are often under disputed control- sometimes they govern themselves, sometimes they're claimed by another power, more often they're left in a state of limbo. This contributes to the rise of piracy. If no flag will swear itself to you, why would you bind yourself to one?