I emailed Rab Gordon, to ask about the difference, between the cheapest & most expensive damacus blades, & their ability to take and hold an edge. He replied:
"Those blades are made for us in India and the Damascus they use is the best quality that I've seen so far coming out of that country - and I've seen and sampled a lot of different supplies from there.
They'll take a pretty reasonable edge but aren't particularly hard so will need resharpening more often.

The High Carbon Damascus blades (made using 1095 and 15N20 steels) are made in Pakistan and are harder, taking a better, longer lasting functional edge.

However, if sharpness and edge retention is very important and your budget can stretch to it then I'd really recommend looking at the Swedish Damascus (Damasteel) which uses two very high grade steels which we have made and precisely heat treated for us in Sheffield."