How do non timed stacking blessings actually work?

[TemplarGFX]

For example the Decimator blessing on this axe :

How do these stacks work? When do they expire? Is it when you hit someone a stack is removed, is it when you break a chain attack all stacks are removed or is it that each stack lasts n seconds and its just not specified?

There are lots of blessings like this, that have stackable traits and no definition of how those stacks function

[InBlack]

Someone needs to figure this out. To me these seem not to be working.

[Lexa]

Intentionally or not, there are a lot of missing status icons that I would expect to be there.
One of those is this status of blessing stacks.