Given U62 is changing W actives (and imbue dice) making high crit weapon damage builds nicer this would be great update for them to also remove the cooldown on Dark Imbuement procs for melee/ranged attacks; they should do it now before the gap between build choices grows even more.
For my build, I like to use From the Shadows which then gives 10sec of Dark imbuement. It is like a mini version of the tier 5. But I use Fatesinger's epic strike with its short cooldown. Then either I renew the dark imbuement with the SD epic strike for another 10 seconds or I rabbit out.
I know that there is some internal cooldown but I am surprised by the dps that comes from it.