This isn't true for everyone, but I really like 18/24 or higher agility builds as 2h or 4 directional polearm user. People will be shocked by the speed that you can swing such an unwieldy weapon. Swing speed matters more in 1v1 than anything else, though. In a line or blob fight, you can hold your swing a long time before picking your target. In 1v1 duels, faster swing speed makes it much harder for your enemy to block or chamber your swings. Combined with high athletics, you can do things like jump and swing into your enemy's head from behind.
I rarely use ironflesh though. That is a very sound and practical investment of points as well.
If you are going for a single weapon type (pure 1H, 2h or polearm) then you don't really need to get WPM. It helps, but if you don't need to spread your WPF you can get away with 100-130 in your only weapon type.
Polearm cavalry, hoplites, pike/long spear users don't need the extra attack speed. They can compensate for their slow attack with positioning and teamwork.