Theory: A/D with scythe + crit

Now, it would require them to tank a little bit, but that's not much difference to daggers, is it? I Theorize that this idea would practically triple the assassin's damage. A dagger assassin NEVER TANKS. "Shadow Step/Snare, strike/combo/kill, shadow step back, heal/cleanse, rinse and repeat"
A Scythe Assassin will tank a bit, but Earth Prayers will make that tanking safe.
A Scythe Assassin will almost never deal as much damage as a decent assassin with a decent combo. Even with a huge Critical Chance, you will not always get a critical in all your hits. Due to the slow attack speed of the Scythe (getting a IAS skill involve getting into Wind Prayers, and you don't have enough points for that), the Scythe Assassin will take longer to achieve a dagger Assassin's damage, but the Scythe Assassin can survive and have a chance to deal damage AOE-wise. Also they have a way better non-elite snare.

I ran an A/D build during the Preview and it works out great. I think I was the one who posted on Guru on the theory during that weekend. Here's the thing:

1. 13 Critical ALWAYS, Use a Crit Mask and a Sup Rune if you have to. You won't have trouble surviving. That leaves us with:
Critical Strikes: 9 + 1 + 3

2. 12 Scythes obviously.
Scythe Mastery: 12

3. Self-healing is achieved via: Earth Prayers:
Somewhere around 8 or 9. Use 9 if you do not require anything else. 8 is for some sort of Snare in Deadly Arts (i.e. Siphon Speed or Scorpion Wire etc.)

Alright here's the skills:
Snare? One of the best melee snare is Crippling Sweep. (obviously for PvE you most likely won't need a snare)
The Elites great for this build is probably Way of the Assassin.
Throw in Mystic Regeneration for the ultimate self-heal.
Assassin's Remedy for condition removal.
Sharpen Daggers for bleeding.
Critical Eye for more critical and energy management.
Obviously a Rez.

Now you got 1 skill opening:
I would choose either Zealous Renewal (it's better than a Zealous Scythe), Chilling Sweep, Mystic Sweep, Reap Impurities, Wearying Strike (Assassin's Remedy removes the Weakness), or Malicious Strike. Sometimes I would take Assassin's Remedy out and throw in Mystic and Chilling Sweep for max damage output.
You can also put in snares, but that's up to you. I can usually cripple someone. Crippling Sweep recharges fast enough for condition removal. On top of that, Scythe is AOE up to 3.

A variation of this build that I have used is use the remaining points from Earth Prayers and dump them into Deadly Arts. I would use Siphon Strength comboed with Siphon Speed and Dark Prison. Your protection will have to come from Critical Defense, which is NOT REALIABLE even with a 100% chance to crit because you have to hit someone. This is a more dangerous build due to the less aspect in tanking, but it snares and deals damage very well. The rest of the skill would be: Crippling Sweep (just in case), Critical Eye, and Sharpen Daggers (rez too). You depend on your critical to deal most of the damage (along with bleeding). If you feel you do not need Crippling Sweep, bring something like Malicious Strike (so you do Critical + bonus damage) or Reaping Impurities. You do not have enough enchantments for Mystic Sweep and Chilling Sweep has too long of a recharge to be spammable.