Specifically the conditions under which they can be used. Picked up some Ironhide and Ironwill Unguent. Once you use one apparently you can't use the other, but there is no explanation as to whether that's really the reason why. You just get a message that says "You can not use an item now." Also, I could not use the item again immediately after the effect had expired. I don't know if there's a cool down to the item or what. I even had an instance where neither were in effect and I still got the a above message when targeting myself. These are just the item I've had experience with since 1.19 but I imagine there are others. Please consider adding more information to items, specifcally use conditions (i.e. whether can be used with other item and cool down time).