I'm a pretty new player and don't own any of these items. I just took my first toon, a rogue mechanic, to level 30, and have tentative plans to run a TWF dagger rogue assassin next. So I'd like to talk about the dagger, Agony.
I've spent a good bit of time trying to figure out which daggers to farm while I'm at 30 right now, this helped occupy my time during the 4 day downtime
My admittedly inexperienced conclusion was that Agony is VERY difficult to beat on paper. I have it as clearly the best DPS for named (non-crafted) daggers in ML23-27 range, under any variety of +W, Seeker, crit range and multiplier increases you care to look at (I'm assuming an Assassin Tier 5 / VKF Tier 4 build right now, with typical feats). I'm not sure about all crafted dagger options, but it's better than TF Tier 1 and ToEE Tier 1 daggers. There is a lot of talk about the Drow Dagger, but my math says that it just can't make up enough ground to catch Agony in DPS even with the expanded crit range. Epic Assassin's Kiss comes closest to Agony for non-crafted, but is clearly behind. TF Tier 1 with Flames gets closest, but the fact that Agony also has Improved Deception (which I found very tough to slot on my Mech) and accepts sentience put its firmly on top of the ML23-27 dagger heap, in my horribly uneducated opinion. I'm actually more intrigued by the Sacrificial dagger and its neg levels than I am by the Drow Weapon master dagger.
I plan to take Agony out of the box, even knowing what I'm passing up with Needle. I have no knowledge of bows, so I'm not smart enough yet to regret leaving Pinion behind. Celestia gives me the most pause, the player base seems to have a love/hate thing going on with Celestia with its easily broken DR bypass. I've found threads where people have given up on it in frustration over the DR bypass being broken by various enhancements.
So I'm also looking for advice on what to take, with a specific focus on how worthwhile Agony is for assassins. I'm imaging equipping Agony at L23 with a sentient gem, maybe a TF Tier 1 dagger in offhand at L24, and then be off and running to L28. I could easily be wrong about Agony, and would love to know if that's the case.
Thanks!