4th Job Information

I highly doubt that the speed difference will utterly wreck you.

I hate slow attacking, it makes the game less fun for me and does severely cut down DPM. It was something like a 12% damage reduction from speed 6- speed 8. Not only that, but it slows down combo charging somewhat. It's just not really worth it to use a slow speed weapon unless it's godly.
A 100 attack Karstan will be better than a 120 attack slow speed weapon as long as you are using an attack potion, considering 1.12xYour TOTAL weapon attack is what you get from it compared to a slow speed weapon. Hell, a mere 150 total weapon attack is enough to put them near even, which even I will obtain, considering the 35 accuracy is worth around 7 attack.