Witnessing usually refers to the GLOBE WITNESS command where a citizen calls upon the city's divine globe to bear witness to his/her activity for up to ten minutes (an Avalon time period). During this time all the person does will be watched closely by the divine globe and reputation gained, ideals enacted, quests completed, combats won, all they do will count for FAR more; both for the player and for the accumulating power of the city's globe - which represents each Avalon year the sum of all citizen act and deed.
See also HELP GLOBE, HELP DUTIES, HELP DEEDS and HELP FEATS.