Acting reasonably and fair within the circumstances of a given the context of a situation by the information provided(intuitively and externally).
Being as objective and fair based on information provided/acquired within the context of the situation.
Being fair given the context of a situation, of the time(1800's fairfully is different than 2011's fairfully), of the rules(ex. laws, covenants,etc)
Not necessarily being perfectly fair from a all knowing/omniscient/ third person movie perspective. It more depends on context and knowledge of the situation based on perspective while trying to be objective.
If the situation falls under being fairfull under omniscient standards whether by luck or other means ,this would fall under being Perfectly Fairfull or Perfectly Fairfully.
If being Perfectly Fairfull but still falling under the definition: Acting reasonable and fair given the context of a situation by the information provided(intuitively and externally while not being overly intuitive or assuming) than that still falls under being Fairfull while just happening to be Perfectly Fairfull.
Roommate A after being told by both Roommate B, C that Roomate D had stolen A's book after finding said book in D's stuff with hateful writing about roommate A that involved D's handwriting fairfully confronted roommate D. Based on the situation it would be fairfull if roommate A pressed roommate D if roommate D shrugged it off. But in order to be fairfull to roommate A could not be a dick when first confronting roommate D. If roommate D was disrespectful and very much an trouble to roommate than roommate A might fairfully escalate the confrontation but only if roommate A was being fairfull when initially confronting D also based upon the information previously acquired earlier. It should be noted that if A unfairfully acquired some of said information( perusing through D's stuff than A is not being fairfull initially and only partially fairfull after the fact)
Sometimes the easiest way to be fairfull is to be respectful and reasonable.