It's a little of both Fantasy and Sci-Fi, and the world is the same as ours, only a few hundred years in the future, when it has been utterly destroyed by war.
As for weapons, there will be a fair amount of futuristic ones (such as, say, swords with blades that flare with electrical sparks, or something. Not lightsabers. We're not that far ahead.) The main weapons will probably be guns, but closer-ranged weapons are probably also needed, because guns will only get you so far in close quarters. Captain Tempest has a very large gun (a detachable one that goes where his left forearm would be; cliche for pirates, I know, but that's kinda the point). There are no magic powers.