I have the same issue, many times when I look at something (potion, spell, ...) there are quite a few unanswered question. Duration of potions (and other effects) is one of those "quicksave and try" kind of things that should really be obvious from the description.
Funnily, just after reading this post I stumbled across a ring with Warding Bond. The missing information you folks mentioned is actually there, just hidden behind another tooltip for reasons unknown
