Lifedrinker enchantment

I think there's something wrong with the lifedrinker enchant (I tested using lesser version).

Using my at will I get :
[Combat (Self)] Your Lifedrinker Weapon deals 35 Necrotic Damage to Target Dummy.

Using dread theft I get:
[Combat (Self)] Your Lifedrinker Weapon gives 0 Necrotic Damage to Target Dummy. (Is it trying to heal the dummy ?..)

Also different powers seem to trigger lifedrinker for different damage, Blades of vanquished armies for example deals 10 damage whereas my at will does 35.

Using BoVa: [Combat (Self)] Your Lifedrinker Weapon deals 11 Necrotic Damage to Target Dummy.


Also, I'm using my main hand artifact weapon which in preview has weapon damage of 995-1295.
Life drinker is 5% of weapon damage, so I should be getting around 65 damage with it, not 10 or 35, what am I missing or is it bugged?

This was tested on dummies in Trade of Blades.

Furthermore, the weapon enchantment tool tip says +5% necrotic damage from weapon damage AND now it gives +1% life steal. What it actually does is give a stacking buff of +1% life steal for 6 seconds, which stacks up to 3 times (you must be hitting 3 targets to get this buff 3 times), is this intended or is that a bug? If it is intended, can it be shown in the tool tip too? to avoid confusion

thanks