... what is the quality of Damascus steel in blades?
Depends on many factors. It's entirely possible to create a 'Damascus' blade with comparable properties as a homogeneous steel. Just as with cheap stainless steels though, not all 'Damascus' steels are very good for making blades; it depends on the skills and reputability of the bladesmith or manufacturing company concerned. Practically speaking 'Damascus' blades offer no advantages over homogeneous steels, their appeal is mainly aesthetic, and they are expensive.
(From an archaeometallurgical point of view, I wince slightly each time I hear of new 'Damascus' steel. 'Damascus steel' never really existed, it was high quality crucible steel made with the Wootz method in India, and possibly in another way from Sri Lanka. These modern 'Damascus' steels are pattern-welded steel; two or more different types of steel forge-welded together repeatedly in order to produce a pattern.)
Oh and as an aside, 'Damascus' shotgun barrels were originally made by welding together scrap (old horseshoes, nails etc.). The pattern was not the objective (at least not the main one). Many original 'Damascus' barrels are not safe to be shot with modern loads, if at all. Many have been lined with modern steel to make them safe to use with modern shotshell loads These days though, 'Damascus' barrels on new guns are all about looks -- damned good looks. (A walnut stocked 12-bore with side-by-side lightly browned 'Damascus' barrels and a colour-case-hardened action, mmmm... now just to decide hammers or boxlock, and to work out how to pay for it!)