Also take the Elusive Target feat CW. The prereq are Dodge and Mobility, which you have to get anyway, and it gives you 3 awesom abilities.

1) If flanked by your Dodge target their 1st attack is against the flanker, catching him flatfooted, rather than you.

2) If your Dodge target power attacks you they get no bonus danage.

3) If you cause an AOO by moving out of a threatened square and they miss you get a free trip attempt and can't be tripped back.

If you also get Improved Trip (prereq Combat Expertise, a Dervish prereq) you can also hit them after a successful trip.

So a successful tactic is to move around doing your Dervish multiple attacks without tumbling and attract those AOOs, with the +4 AC drom Mobility, and everytime they miss you get a free trip attack and on a sucessful trip an additional followup attack.

If you want to take the TWF route then you might want to look at the Ebberon Valanar Double Scimitar. It gains the Dervish Scimitar effect and gives acess to Exotic Weaponmaster which has some useful stuff.

Another option is looking at the Flameblade spell. If you can get the ability to use it via ring of spell storing/friendly druid or magic item, along with the empower and energy substitution metamagic feats you can truly rock with touch attacks to hit. This also allows a pure dex build using weapon finnesse to wield the scimitar flameblades (scimitars are light weapons for Dervishs) and power attack.

Stephen E