Thanks everybody for your responses!
Oathblade: - Forgot to include this in my earlier reply. Yup this does seem really good to me, it wins compared to all the rest in this category of non-raid weapons. Probably will try to farm up Commendations. That's another topic though! That could take a while considering how few i've pulled in my past 2 characters that i got to 25.. Definitely seems harder to me than farming Challenge ingredients.
Drow weapons - I really like the 'feel' of this. Hard to farm but not hard to find on the AH/AsH. Even without the ability i'm looking for, I like it. It just lacks a Red Slot.
Khopesh of Water - I've seen them in action and have always liked this weapon! Just too bad that it will require a feat. If paired with Allegience, it could be interesting.
Sacrificial Dagger - This looks like it would be useful on EE. Same effect as Nightmare but with less DPS..
Envenomed blade - As much as how cool it looks, i really don't like this weapon. Found the DPS bad and never used it in any of my char's.
Comyrian Weapons - Never tried it coz i thought the price was too much, but will look into it again.
@ Encair, ive come close to actual number crunching with excel or calculators but luckily never had to really go that far.. There was most often a clear winner in what weapon i would use.. This time though there are more choices so I might just end up computing them. This is my 1st TWF Slashing life. Last 3 toons I played TWF Piercing, and before that THF.
@ Phaeton, like IronClan said. I find it useful in quests like Running with the Devils Hard or Elite(I threw away my Cruel Nobility and that was my most effective weapon against them). They can heal all their HP in a few seconds so the best bet is to kill them with 1 hit. At this level range mob HP is also not that high so they can still die with 1 Vorpal blow.