Hi tanmay,
i never find any free tool because xml incident export is not one xml file but an aggregate of xml file of each incident.
So usually for my customer , i used to devellop some python script to analyze this xml export and then produce automatically their report in xml or pdf.
But if someone know one free tool which works fine, i will also be happy to know it. Or may be you can try IT Analytics (it is a symantec free tool but you will need some servers to run it so it is not so free to use), depending on which type of report you need.
Regards.