Yes, but that item is required regardless as you push GR's even when not using Unity.
Each follower has a legendary relic with the power "Your follower cannot die". It is mandatory. Your follower will never do any damage, but the buffs they add are significant and go away while they are dead, which happens a lot without that relic in high torment.GR's.
You can craft the leg with the cube upgrade rare recipe. Other than that, followers should generally be equipped with crowd control/debuff type gear and most likely an Oculus Ring. Shield of Deflection, Thunderfury, Ess of Jordan, etc.
And the Templar is pretty much where it is at..