SHSH blobs are useless for iPhone 4S/5, iPad 2/3/4 and iPod 5 at the moment. No word on if/when they will be of any use. There is no way for you to upgrade your 6.0.2 iPhone 5 to 6.1.2. Your best bet would be to jailbreak 6.0.2 (yes you can jailbreak 6.0.2) and try not to break it so you don't have to restore because if you restore, the only way to be successful will be with 6.1.3.