Pure crit in Renewal / Revo Classic isn't that good for 2-1 & 2-2 classes because Crit doesn't ignore Defense, only flee. If you're planning on going full crit, you should have 1 dex only. That also means that you don't have HIT for your Sonic Blow & Grimtooth
Dual Attack on Dual Daggers will be expensive because of the cards and it is pretty bad against large monsters because of the Size Penalty. Also, you can't use your Katar skills, you only have your dagger passives & venom splasher.
Dual Attack on Katars is pretty efficient in Revo Classic. I've read about other people's reasons on Assassin Builds and I was convinced that DA on Katars is the way to go. Also because when u get DA - Katars, you have high Dex for high Hit so you have the best stats for your Sonic Blow & Grimtooth. It is cheaper than DA - Dual Dagger because it needs less cards.
Conclusion, Dual Attack Katar is the best
Now the build,
In Renewal / Revo Classic, maxing a stat is a big no no. I saw a DA - Katar build that has about ~30 ish LUCK so he can get 10% Critical Rate which translates to 20% Critical Rate when using Katars. With that build, you now have a mix of Dual Attack & Some Crits on your DPS which I think is pretty good.
His build was pretty hybrid with stats allocated to:
Str, Agi, Vit, Dex, Luk
IDK where it is in the forum now because I saw it more than 2 weeks ago