I was going through the static loot list and noticed that there is only one named dwarven axe. Now there might be other weapons that are just as few but I wasn't going to go through and look for every weapon. There is a dwarven axe called Sever that drops in Tome of the Untold Legends. While in Mindsunder alone there are 20 Dream Edges and 5 Rah's Might. Each one a little different but they are all kama's and quarterstaffs respectively. The only way I see to get any special dwarven axes is to craft greensteel but then all weapons can be greensteel from what I've seen.
As for high end loot there is nothing more annoying then a level 20 character getting a +1 weapon or +1 stat item from a level 18 to 20 quest. I was getting similar items at around levels 12 to 15. the only main difference between the items was the minimum level requirement. I would suggest keeping the +1 and 2 stuff for the low to mid levels and the +3 to 5 stuff to the mid to high end. Most 18 to 20 characters would more than likely keep the +4 or 5 items and either sell the +3's in the AH or to the vendors.