I would say duel wield scimitars with improved critical feat. Possibly a speed weapon or boots of speed. You would have a 15-20 crit range, high number of attacks, and with the dervish your penalty for TWF with scimitars is treated as if they are light so only a -2. The attack bonus is normally pretty high with a decent strength and some mid level enhancement on the weapon. +2 or +3 is good. If you can do some customized magic items I would pump it all into attack. Their is another feat for crits, I think it is Power Critical from the complete warrior that gives you a +4 on back up attempts for crits. The average damage per hit is not normally that high, but I had one with 8 attacks a round normally hit on 4 and critted on one per round. The only problem is undead, the way I handled that was back-up scimitars with a +1 undead bane, ghost touch.