All right, it’s probably a bit late for suggestions like this. But still, if Crate decides what they need another “layer” for balancing or wants to bring some unique buffs in specific slot - why not? Relics are the last gear slot without augments.
Think about this - for example, how about augments with devotion procs buff? Like % increased effect of Chaos concellations procs. Or -% cooldown for Order. Something like this. If this not enough - it’s may be also some tradeoff buffs here. Like for example - additional aura but at the cost of reducing max health, etc.