Anyone who has played on the Ruairi server, before the Iria update, should be well aware that an items max durability had been able to be modified. Who here remembers the 50 durability Claymores and the whole caste of 200+ dur armour that was being sold by a few less then kosher individuals?
As for being able to restore the ability to its full max, this would be a bit more difficult since when an item log is created, the information and associated ID's are stored serverside, and as such would disallow any unscrupulous editing from all but the most devious modders.