Hello Pralhad,
I worked and I'm still working hard on the collection of insecure examples of code concerning Windows Phone apps - my idea is to integrate both the testing guide and the MTT with WP-specific details. I’m going to share my research results (codes + exploiting techniques) with the Project in the next weeks, and update all the stuff with the release of Windows 10 for phone - also including Universal Apps pentesting methods and secure coding.
Btw, MWR's paper is an awesome resource on the topic and, on the basis of my knowledge, the only publicly available doc on WP 8 app security.
If you need further details, feel free to drop me an email.