Creatures on Vissidal have a loot profile that is modifed by a "Quality Flag," which influences the liklihood a stat will be on the higher end of the possible range of values. Because several stats need to be in the high range for an item to be considered really good, the principles of combinatorics work to make not just more likely, but far more likely to find a good item on Vissidal than any other place currently. Django verifies this on Turbine's Forums in this thread: Add in melee def max that ranges from 1 to 5 and you drop to 0.5% (half a percent), or 1 in every 200 swords that drop.