When on earth do you think you can reduce the delay of the windstriker to 18 ??
Lets say you used epic haste .. 40% ... chanter haste 70% .... fleeting quiver 20% ...(not thinking about bards here)
The current haste cap as i understand it is 100% (used to be 85) now, im not sure that the quiver can take you over that, but for a laugh we will assume it will.
So thats 130% haste ...
windstirker ... 60 delay ... so takes 1 minute to shoot ten shots...
Now with 130% haste you will shoot 23 shots in the same time ..60/23 = 2.6 ...
Almost impossible to get to 18 you would need over 200% haste which isnt possible.
As far as im aware the max haste is 100% so the max haste on this bow = 30 .. not 18..