Was damscus used in XV century?And if answer is YES -was it used for sword blades?What is the main period and territory of damascus use?What are the pros and cons for using such material?

Try searches on damascus, wootz, and pattern welding, I'm sure you'll find plenty of info. There's a bit of necessary semantic clarification - Damascus was a trade city through which Europeans became particularly familiar with middle eastern / Indian wootz-based arms, but "damascus" as applied to blades has become a casual term for decorative pattern welding (especially in modern custom knives). You'll have to look up the details on wootz, which has a very specific appearance and functionality (I'm not the best person to talk about this), but I believe that it required very specific forging methods that European smiths were not aware of, so it therefore attained a kind of mysticism. I don't think pattern welding was really seen at all on post-medieval European arms, but it was the key forging technology of the Anglo Saxons, who were only able to forge long cables and then had to twist and weld them together to form a full-length sword.

This is really not my strongest field in arms and armour so the above is a very sketchy outline; please search on this site for more info and hopefully others will correct my less precise statements. :)