Currently we assume every DK has 2 charges of Death Grip but did not account for Death's Reach resets.

Quoting someone on wowhead: It feels like you need to get the killing blow for it to work? That makes it useless in group content, including in pvp where you'd think it would be really strong.

Not every DK plays 2 charges of death grip and not everyone plays Death's Echo.
So probably should make it opt_charges. And the reset does not trigger that often.