Unfortunately our weapon combo depends on the situation. I'll break it down into categories Best DPS Combo
This is simple, take the daggers that have the two highest base DMG. Ermine's has slightly higher DPS due to the lower delay.
Runner up: Ermine's/Adder +1. This is a beast of a combo since you will actually get more tp over time than azoth/ermines. But you will see slightly less WS DMG and won't have the extra acc from azoth. Plus, good luck getting an adder +1... Best WS combo
: Tie between Azoth/Ermines(or /adder+1) and Azoth/BK+1
Since most of us will be using either dancing edge, Pyrrhic kleos, or evisceration, it's important to have an offhand dagger that can contribute to all hits possible. BK+1 will give an extra 10 attack on all hits which is nice. But you also have to consider your overall DMG when TPing which is why the higher DPS daggers will give you a slight edge in that department. Best TP combo
Here's where it gets tricky. If you're PURELY going for TP and not worried about DPS DMG or WS DMG and lets say, for arguments sake, you are hitting for 1 DMG on each dagger, your best combo for building tp is probably going to be an Ogre jambiya with augmented STP offhanding CUK. And before any of you other people jump on me, I know that your DMG will be crap as I already stated earlier, but again, if you're just going for TP such as main healing in a merit party and you have a good amount of haste, this combo will be tough to beat.
In addition to this, if you have a brd friend and a decent haste setup, its hella funny to use these 2 daggers under haste samba/saber dance/2X SV march. You can literally solo a G colibri under these settings (provided that it doesn't spam pecking flurry on ya)
Now if damage has to be considered (in most cases it will be) then simply go for the best DPS combo stated above. Best solo combo
This is another no brainer. High DPS with 4 acc, 4 agi, and 12 evasion overall. Gravy if you're soloing Amemet too XD. Best support combo
I really can't stress enough how helpful offhanding an adder is. The evasion down procs quite a bit on just about anything you fight. The effect only lasts a minute and it doesn't stack with the effect from PK, but it does stack with steps and desperate flourish to help both you and your party hit that much more on evasive mobs. That combined with your azoth's acc will also help your acc to keep sambas on the mob.
And now the stuff to avoid.
Cobra unit knife: Yes I know I said that its the fastest way to get tp, but in most other situations you're going to want the DPS from the other daggers
Kard: Its CHR doesn't justify its low DPS. NEVER use this dagger...
Ogre Jambiya: Its good to use if you can't afford azoth/adder yet or still farming for ermines. Until I see one with +6 DMG I really can't recommend using one full time in main hand.
Joyeuse: As stated by kaishen, joyeuse's low acc due to D rating can't justify its use even with the 45% DA rate although it WILL come out on top in terms of TP in some situations but only BARELY. But with that considered, you will also do less overall damage. If you need math check this link here
(just try to ignore the rest of the BS on that page...it is KI after all >.>)
Terpisichore: Whoever designed this dagger needs to be shot...crap DPS and you can't get all of the aftermath effects until you do WS at 100% tp, then again at 200% and 300%. If there's any mob that will last that long I guarantee you that you won't be fighting it on DNC. Unless your a completionist (masochist would be a better term) don't bother wasting time getting this dagger.
Well hopefully that wasn't too long, but should give you a better picture at what options are available and why. Edited, Aug 28th 2009 6:31am by Kalisa