Every millisecond matters when you try to outswing someone in addition to the slightly increased damage. It's all up to you what you want. I don't think filling up WM for one weapon is worth it at 5WM and below, though. 6-7 can be pretty helpful, though. WM isn't really worth it until you reach a very high level, since increasing PS or ath is more of a benefit.
24/15 is a good build, especially if you're going to use some armor. Remember to max ath and PS. With medium armor, I would balance out those numbers a bit more.
