Nidalla's Hidden Hand and (non) stacking posion

So I was using the target dummies to test poison stacking and found out that Nidalla’s hidden hand doesn’t work quite like I thought.

From the numbers I was getting on the dummy some things were obvious - for example there can only be one Nidalla’s stack on a target at a time, perhaps this seems obvious to you but I had figured you’d get a potential one stack for Shears, one stack for Quick Cut, and one for Whirling Death.

Is this the intended (non) stacking mechanism for Nidalla’s Hidden Hand? It seems off the in-your-face poison melee line would be 2nd string to the arguably safer Dreegs line. And I am aware that melee gets the always fun Nidalla’s Justifiable Ends…but there isn’t really anything about a caster preventing them from using that for the occasional hard target.

So no one has thoughts on hidden hand? Is there perhaps something about Nidalla’s hidden hand that I’m missing - or is poison really best left to dreegs based characters?