Could be just me but in campaign I often find myself with a couple thousand shards more than I can spend after a point. So why not gain a consumable item that is activated by using shards?
As to the best way to implement something like this? Not sure to be honest.
Do you equip it pre match or do you pick it up during the match?
Is it one time use on activation or reusable with a cooldown and reactivation charge?
Pve only or include all game modes?