To follow up on this: I did some digging on the WotC boards, especially in the Sorcerer threads. Apparently, there is someone that digged at CS enough times to get to the DevTeam, and the word of god seems to favor my position (weapon powers not applicable to implements) consistently. This is from someone who pestered the DevTeam directly until Weapon Focus worked for Staffs.
You can find the link here:
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Its not directly from CS or the DevTeam, but we can at least contact Crimson_Lancer over there if you want some more direct evidence.
Interesting wrinkle in this, though: From their ruling, it seems that it is clear that the reading should be "You cannot use weapon powers when using the weapon as an implement." But, as noted by others, Flaming Weapons are not used during the attack, but before. So, in theory, the power could be converted to fire/whatever... but, here's the kicker: It wouldn't gain the Fire keyword (so feats/powers/etc. that require the keyword wouldn't work. So, using a frost dagger and the wintertouched combos would not work; see question 15 of the FAQ for this one.
So, the summary:
- You can't use weapon powers when using the item as an implement (baring, of course, exceptions in the power themselves)
- Powers of a weapon can be used when not being used as an implement
- ... but, any keywords those powers grant do not apply (you only gain keywords when using the weapon power with the power it augments... which you can't do for weapon powers with implements).