Here's the quote from the Draft
FAQ:
Q: Do weapon special rules that say ‘a model equipped with this weapon’ or ‘this weapon’s bearer’ take effect even when not used as the attacking weapon?
A: Yes.
So, if the weapon says that the user just has to be equipped with it, such as in the case of the Kiss, then it functions even when not "attacking" with it. In the case of the Solitaire, this means that it still trades one attack in for a Kiss of Death attack, and that all of his attacks are counted as being made with the Caress. Now, we'll see what the Harlequin
FAQ ends up stating, but I'm pretty confident that this means that a model that scores a to-hit roll of "6" with a Caress inflicts the 1 wound at AP2, but continues with that being a hit normally (including if it was the Kiss of Death attack).