Hey all,
Myself & @OminousGMan have been following this up further with the team and passed on all feedback mentioned here and more recently in the Jeweled Golden Grasp & Eveline Locket threads, as you have mentioned these item bonuses are not in line with what is expected in comparison to other items.
There will be a change going out before the weekend that will bring any items currently at +4 at Legendary up to +5 so the bonus is cohesive across the board! 
Jeto (she/they) - Support Human 