Battara,
I don't think the references to Hz. Ali necessarily makes the owner of this yatağan a shia since bravery of Ali and his valour in battle are common themes in Islamic literature. (by the way zulfikar was Ali's sword). But the title of the owner "Ağa/Agha" tell us that he was possibly from the military class, that title was usually used for janissaries.
For the seven sleepers, I am not really sure, but there was a similar discussion in this forum and Teodor offered an explanation based on his talks with a Bulgarian scientist, you can find it here:
http://www.vikingsword.com/vb/showth...light=sleepers
Best,
Zifir