I still rate schaefers as the best pvm weapon for a frenzy barb, using one of these and a beast weapon (caduceus for barb with mace mastery) is devastating for monster packs, and a 5 frame attack is possible with only 15% ias on non-weapon items with a level 24+ frenzy and the level 9 fanat that you get from beast. Beast and Doom for a frenzy barb would make more sense in a PVP environment however, particularly for an anti-caster barb (where shields mean nothing.)
I would suggest a double swing build instead. Beast's Fanaticism plus the natural speed of Doom/Beast zerker axes would grant your barb maximum double swing speed without any IAS at all. This frees up the rest of your gear for life, resists, skills, etc.