Jared On a ship, if you spin the whole thing all equipment would be constantly spinning, including weapons, unless you had very advanced fire control systems, I doubt it will b easy to aim point defence and such while spinning. Unless you had an extremely massive and dense field of dust, it would probably disipate and spread out. Unless it Is shot at unbelievable speed, it would be dodged if a ship is agile enough. Yes it could be used at close range at such, but if jousting a the high speeds the dust could travel too slow to hit. Anyway, how do you fire this dust? I guess you could use some sort of big scattergun, but it would have to be big to fire a big cloud, which would be extremely hard. Jousting would probably still be massive distances apart, getting into ramming distance would be literally impossible. Laser weapons could probably ware down the clouds enough to make them less harmful if they are on a unavoidable collision course.