Inspired by this:
If a thief with ki focus proficiency (via a theme) finds herself wielding a ki focus enhanced dagger and an implement power that qualifies as a melee basic attack, does the thief get to add sneak attack damage dice? Furthermore, if she charged with this dagger-as-implement, with the feat "surprising charge" what damage would she add to her charge?
The wording of sneaky staff strongly implies weapon-only, and the coding of character builder reinforces that restriction.
Edited after @wax eagle corrective comment
By RAW alone, it seems to be maybe to both questions.
Sneak AttackDDI is defined in terms of weapons alone: you can deliver it when hitting with a light blade, hand crossbow, shortbow or sling; but it does not explicitly limit the usage to Weapon (keyword) attacks only. This implies that hitting with a dagger allows the use of sneak attack damage, even if the dagger itself is an implement. With regard to Ki Focus, at least 2 cases can occur.
Case 1, in my opinion, leads to a straightforward yes answer (you are sneak attacking using a dagger).
Case 2, as the discussion pointed out by @wax eagle explains, is a disputed field. Rules wording is prone to multiple interpretations. On a side, following the common natural language, you are using a dagger to land a hit on your target (sneak attack bonanza); on the other you are using a power from a training manual (implement), and the dagger is a mere vessel for this power (in fact, you are not applying the dagger +3 proficiency bonus).
About Surprising Charge... I don't have access to the rules right now, but if I remember correctly, the 1[W] notation isn't tied to the Weapon keyword. So, charging with a implement-based MBA wielding a dagger-as-implement should grant the additional 1d4 die of damage; while doing the same with a dagger-infused-with-training-manual-ki is still a disputed question.
Disputed.
I've seen rogue-wizard MC builds that use the dagger as an implement and because the rogue is "using" the dagger in the attack you may still apply sneak attack. This would the exact same thing with the ki focus. The ki focus is channeling its energy to the dagger which is being used as the implement.
However, there is significant discussion as to whether this works in the context of the assassin.
I would say that it works, however depending on how the ki focus rules are read it could definitely be ruled the other way.
No
Here is my explanation of why. I will use the Monk and Vampire classes as examples.
The Monk delivers most of his attacks as melee attacks. He uses a Ki focus to imbue his abilities. This means that his attacks, no matter where they are coming from, are charged with power because of his power source. That means that his powers are coming from his raw ability rather then a weapon. Because of this, all his attacks are Implement, not Weapon. So when he delivers the attack, it doesn't matter what he's using to deliver the attack. A fork still does 1d8 points of damage on an At Will attack.
The same with the vampire. A vamp draws power from their Shadow power source, and a Ki focus helps to focus and increase that power. However, what is he using to attack with? Claws, their fists, their teeth, and maybe their mind. At no time are they utilizing a weapon for their damage. They might pick up a sword, but that is not what their powers are using to deal damage.
Now, if you use a normal melee basic attack with a weapon, this then works. However, if you are using a power that counts as a melee basic attack and it does not have the Weapon keyword, you are still not using a melee basic attack through a Weapon. You are using it through the Implement again, because of the nature of the power source. Because of this, sneak attack won't work, as it requires a Weapon to use.
Sneak attack specifies, IIRC, rogue powers. A ki attack would be a monk power, not a rogue power. So you would not get Sneak Attack from the use of a monk power.
