Last I checked, +all skills and +specific skills work, but not +barb skills. That said, I personally would either use a COA for tankiness or Gullies for pure DPS, then just socket them with whatever. Since youre a singer though you could probably stick with pure offense since your wcs will make him pretty tanky
Depends on your budget, but gullies + whatever socket, maybe ber or um depending on what he needs + fort(or duress on a budget) + dual grief pb or grief + last wish/death for some more CB.
Just my opinion tho