It depends on the metals used to make the Damascus. Some can be hardened very well, and some stay soft no matter what. Some contain ONE steel that is hard, but the other is either iron, or soft steel. Then, it depends on the design of the Damascus whether it will hold a good edge.
There are no hard and fast rules. In ancient times, the only reason to make Damascus steel was to produce a harder steel. Today, people are out to make " pretty", and a buck, as often as they are interested in making hard steel blades. You have to know the source of your Damascus billet, or blade. Getting a soft damascus blank, or billet today, is usually the exception, than the rule.
Check the dealers who advertise in BLADE magazine- as they are focused on producing Damascus steel for knifemakers. A phone call can generally get you the Rockwell Hardness of their steels by asking.