the reason you would want grief/lastwish over 2xgriefs would be to do uber trist and last wish won't proc with ww. idk y arachnid> over SoE or rends> LoH. idk why you would want an soj on a barb. it doesn't have any mana leach either. it must be for a weird berserker barb build. i would get a mana leach ring, laying of hands and a string of ears and make a ww barb with 1 point to frenzy. then trade the rends and put the soj and arachnid on your sorc. if you want to use that exact gear on a barb then make a berserker barb but put enough points to double swing to have 0 mana cost. and yeah you would want to go with an act 2 might merc.
D2:R