Chance to cast Static Field will not go off while whirlwinding, so
you may want to reconsider. However, if your mind is set on the
weapon I would choose a Giant Thresher as it has range  and speed
-10 so with Crescent Moon's 20% IAS it will hit the second whirlwind
break point. A better option might be a Shaelx2 Ogre Axe or a Cryptic Axe
with an IAS jewel.