Energy Ability Damage

[moritheil]

You need to look at each situation. For the Death Knight's touch you'd have to ask yourself if the Con damage came from negative energy and was thus thwarted by Death Ward. Another way of viewing this would be to ask, "Do you get the Con damage if you do not get the base negative energy damage?"

I lean towards denying the Con damage, but I think that a very, very strict rules reading might allow it as the Con damage is not actually specified as coming from negative energy.

This is tangential, but I went and looked it up because it was contrary to my understanding. The hit point damage - and only the hit point damage - is specifically called out as being negative energy. In the next sentence it states that a touch from a death knight also deals 1 point of Con damage. It would be far more intuitive to simply say "and 1 point of Con damage" in the previous sentence if the Con damage was also due to negative energy.

An analogous concept seems to be that injury poisons require the user to deal hit point damage in order to force a save, but contact poisons do not.