I have not thought of how it would look, I am going to discuss function in this post.
This is how I see it: dispel would be a PvE item only. It has a one time use then you must wait (x) amount of time (possibly longer than a shield regen) to use it again. Dispel would cause a debuff that prevents enemies from attacking. Duration of the debuff would be based on star level, starting at two seconds and maxing out at six seconds. This new offhand item would best function as an AOE.
This sounds a bit... Well... Useless, to be honest. In PvE we usually just rush over and destroy whatever is near. If this would be anything, it should be a consumable with rarity in par with the recon flare. That wouldn't have a cooldown, but you couldn't just render enemies helpless every ten seconds.