I still say their use would be perfect for two situation, one keep them unique items and remove the battle restriction. Two remove Unique status and keep the "Not in Combat" restriction.

A third alternative would be to remove both restrictions, increese the cool down, and restrict the item to open world only (Similar to how the icirrus feathers can only be use in PvP)

It's just a shame that their use is so incredibly limited simply because they are unique AND unusable in battle, If nothing was ever going to be done with them it may have simply been better never to impliment them to start with.