I don’t play rogue so I had to look this up. It seems that Grasp of Shadows also does:
Lucky Hit: Damaging a Vulnerable enemy with a Marksman or Cutthroat Skill has up to a [24-34%] chance to summon a Shadow Clone that mimics your attack.
Which is the unique part that (I assume) you can’t get anywhere else. If you don’t value that, then don’t equip the unique. I often don’t look at a unique in a 1:1 bubble between what it directly replaces, but rather if I value the unique effect and if I can compensate with on other gear or cope with the loss of other stats to get that effect.
If you only look at the affixes of a unique and compare it to a legendary, then it should be lesser. The unique is often not powerful because of its stats, but because of the effect changes you can’t get elsewhere.