Question about weapon speed levels.

Well, I'm not entirely sure but, most of the skill times given are based on the assumption that your weapon is normal(6). To convert to a different speed, you multiply the skill time by (10+x)/16, where x is equal to weapon speed, don't forget to include booster, and then round to the nearest multiple of thirty, you usually round up, I think, but sometimes you round down, and some skills, like hurricane, have fixed speeds.