Only one shael is needed to max the speed on a WW barb - so I suggest that. For the other socket, I find an Ist is great if you are Mfing. I suppose Amn if you need more life leech or Ohm/ED jewel for more damage.
Good question??
Sheal is not needed...ohm is too expensive....maybe an elemental damage jewel? 1-100 lightening.....or even something to give cold damage could be of benefit.